Last Updated: January 2008
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This page is a list of Questions, some Frequently Asked, some Not
So. It also includes Frequently Requested Web Links. It is
intended for use by anyone interested in learning more about Solaris 10
Zones/Containers.
If you would like to provide feedback on this FAQ, please send it to zones-discuss AT opensolaris DOT org.
A date appearing after an answer provides the most recent date the
answer has been updated. Answers with 'old' dates, or no date at all,
might not provide the most recent information. All answers without dates
were current on June 14, 2005.
Q: What is a zone?
A: A zone is a virtual operating system abstraction that provides a
protected environment in which applications run. The applications are
protected from each other to provide software fault isolation. To ease
the labor of managing multiple applications and their environments,
they co-exist within one operating system instance, and are usually
managed as one entity.
Q: What is a container?
A: A zone which also uses the operating system's resource management
facility is then called a container. Many people use the two words
'zone' and 'container' interchangeably.
Q: What types of zones are available?
A: The following types of non-global zones are available:
Native:
The default non-global zone is the native zone. It has the
same characteristics as the Solaris 10 Operating System or later release
that is running in the global zone.
If you have configured your system with Solaris Trusted Extensions, each
non-global zone is associated
with a level of security, or label. Labeled zones can be configured
starting with the Solaris 10 11/06 release.
For more information, see Solaris Trusted Extensions Installation and
Configuration.
Branded Zones:
It is also possible to run a different operating environment inside of
a non-global zone. The branded zone (BrandZ) framework extends the
Solaris Zones infrastructure to include the creation of brands, or
alternative sets of runtime behaviors. "Brand" can refer to a wide range of
operating environments. Currently, there are two branded zones:
The lx branded zone introduced in the SX DE and
Solaris 10 8/07 releases provides a Linux environment for your
applications and runs on x86 and x64 machines. For more information,
visit the OpenSolaris Community: BrandZ.
Q: What is a global zone? Sparse-root zone?
Whole-root zone? Local zone?
A: After installing Solaris 10 on a system, but before creating any zones,
all processes run in the global zone. After you create a zone, it has
processes which are associated with that zone and no other zone.
Any process created by a process in a non-global zone is also
associated with that non-global zone.
Any zone which is not the global zone is called a non-global zone.
Some people call non-global zones simply "zones." Others call them
"local zones" but this is discouraged.
The default zone filesystem model is called "sparse-root." This model
emphasizes efficiency at the cost of some configuration flexibility.
Sparse-root zones optimize physical memory and disk space usage by sharing
some directories, like /usr and /lib. Sparse-root zones have their own
private file areas for directories like /etc and /var.
Whole-root zones increase configuration flexibility but increase
resource usage. They do not use shared filesystems for /usr, /lib, and
a few others.
Q: Can I create a zone which shares ("inherits") some, but not all of /usr, /lib, /platform, /sbin?
The original design of Solaris Containers assumes that those four directories
are either all shared ("inherited") or all not shared. Sharing some and not
others will lead to undefined and/or unpredictable behavior.
Q: How do I get zones or containers?
A: Operating systems based on the OpenSolaris code base may elect toinclude support for zones.
Sun provides Solaris 10 and Solaris Express, each of which include
complete support for Zones.
Q: What hardware can utilize zones or containers?
A: Zones and resource management are all software feature of
OpenSolaris, and by extension, Solaris and other operating systems
based on OpenSolaris. As software features, they do not depend upon any
specific hardware platform. Any hardware that runs OpenSolaris
or one of its distros, e.g. Solaris 10, will be able to have these
features.
Q: Will my software run in a zone or container?
A: Most Solaris software will run unmodified in a zone, without needing
to re-compile. Unprivileged software (programs that do not run as root nor
with specific privileges) typically run unmodified in a zone once they
can be successfully installed. Installation software must not assume that
it can write
into shared, read-only filesystems, e.g. /usr. This can be circumvented by
adding a writable filesystem to the zone (e.g. at /usr/local) or using a
whole-root zone.
However, there are a few applications which need non-default privileges to
run - privileges not normally available in a zone, such as the ability
to set the system's time-of-day clock. For these situations, the feature
named "configurable privileges" has been added. This feature allows the
global zone administrator - the person who manages zones on a system -
to assign additional, non-default privileges to a zone. The zone's
administrator can then allow individual users to use those non-default
privileges.
An applications which requires privileges which cannot be added to
a zone may need modification to run properly in a zone.
Here are some guidelines:
An application which accesses the network and files, and performs
no other I/O, should work correctly.
Applications which require direct access to certain devices, e.g. a
disk partition, will usually work if the zone is configured correctly.
However, in some cases this may increase security risks.
Applications which require direct access to these devices must be modified to work correctly:
/dev/kmem
a network device
Starting with OpenSolaris build 37 and Solaris 10 8/07, a zone
can be configured as an "exclusive-IP zone" which gives it exclusive
access to the NIC(s) that the zone has been assigned. Applications
in such a zone can communicate directly with the NIC(s) available
to the zone.
Applications running in shared-IP zones should instead use one of the many IP services.
For more details, read the white paper "Bringing
Your Application Into the Zone". Note that changes have been made to privileges, IP types, and other areas used with zones since this paper was published. For current information, also see the administration guide. [November 2007]
Q: What applications are certified to run in
zones or containers?
A: Supportability of an application running in a container is evaluated
by the ISV. Some software vendors treat Zones as just another feature
set of Solaris, and do not feel a need to specifically certify their
software to use zones. Others have specifically certified their
software to use zones. Applications which have been reported to be officially supported include those in the following list. For more details see the section
"Application-specific Information"
Veritas
Storage Foundation 4.1
- for Solaris 10, requires the newest versions of patches 119255, 118344, and 118844 for x86/x64, or the SPARC equivalents of those patches
Q: How can I use the Solaris 'Explorer' program to collect information on my zone(s)?
A: Explorer 5.0 can be run on Solaris 10 in a global zone. It can be used to collect information on containers (non-global zones) with the -w option.
Q: What changes have happened to zones since it was first released?
A: See the OpenSolaris
project page for changes made since the initial release. [September 2006]
Q: How "big" is a zone?
A: If configured with default parameters, a zone requires about 85MB
of free disk space per zone when the
global zone has been installed with the "All" metacluster of Solaris
packages. Additional packages installed in the global zone will require
additional space in the non-global zones. SVM soft partitions can be used to
divide disk slices and enforce per-zone disk space constraints. When
performing capacity planning, 40MB of additional RAM per zone is
suggested. Applications do not use any "extra" RAM because they are
running in a zone.
A zone installed using the "full-root model" will take up as much space
as the initial Solaris 10 installation, which will be more than 500MB
in most cases.
Q: How many containers can one copy of
Solaris have?
A: While the theoretical limit is over 8,000, the practical limit
depends on:
The amount of hardware resources used by the applications versus
the amount available in the system. This includes the number and
processing power of CPUs, memory size,
NICs, HBAs, etc.
What portion of the installed zones are actually in use. For
example, you can create 100 zones, each ready to offer a web service,
but only boot the 10 that you need this month. The unbooted zones take
up disk space, but do not cause the use of any extra CPU power,
RAM, or
I/O.
Consider these examples which worked:
40 zones, each running five copies of the Apache web service, on
an E250 with two 300MHz CPUs, 512MB RAM, and three hard disk drives
totalling 40GB. With all zones running and a load consisting of
multiple simultaneous HTTP requests to each zone, the overhead of using
zones was so small it wasn't measurable (<5%).
Q: Can each zone run a different Solaris
version?
A: No. All of the zones use a single underlying kernel. The
version of the kernel determines the version of every container in that
domain.
Q: What types of re-configurations require
a non-global zone re-boot?
A:
Adding a device to a non-global zone.
Binding a zone to a pool.
Q: What types of re-configurations
require a complete system re-boot?
A: We are not aware of any.
Q: Can containers be clustered?
A: Yes, but not without adding additional cluster management software.
As of this writing, Sun is developing extensions to its Sun Cluster
software, so that Resource Groups can be placed within non-global
zones. <Veritas/Symantec> has also announced support for Zones in
the Veritas Cluster product.
Q: Can I use SysV shared memory between
containers?
A: No. This would violate several security principles.
Q: Can a zone include multiple zones (aka "is
the containment model hierarchical")?
A: No, the model is stricly two-level: one global zones and one or more
non-global zones. Only the global zone can create non-global zones, and each
non-global zone must be contained within the global zone.
Q: Can I automate the process of entering
system information, e.g. with sysidcfg?
A: Yes, after a zone has been installed, copy a sysidcfg(4) file
to the zone's /etc/sysidcfg before the first boot of that zone. Also,
execute the command
touch
.NFS4inst_state.domain
Q: Can some local zones be in different time zones?
A: Yes. Each non-global zone has its own copy of /etc/default/init, which
contains the timezone setting. You can change the line starting with
"TZ=". The recognized names of timezones are in
/usr/share/lib/zoneinfo. For example, Eastern Standard Time in the USA
is defined in the file /usr/share/lib/zoneinfo/US/Eastern. To set a
non-global zone's timezone to that timezone, the line in /etc/default/init
would look like this:
TZ=US/Eastern
Q: Can some non-global zones have different date
and/or time settings (i.e. different clocks)?
A: Although different zones can have 'be' in different time zones, each
zone gets its date and time clock from the same source. This means that
the time zone setting gets applied after the current time data is
obtained from the kernel.
If you would like the ability to have different clock sources per zone,
please add a call record to RFE 5033497. [August 2005]
Q: Can I label my terminal windows with the name of the zone I'm logged into?
A: Yes. After logging into the zone, enter this command:
Q: How can I add a filesystem to an existing zone?
A: There are four methods. The following list uses UFS examples, but other types of file systems, such as HSFS and VxFS, can be used in the zonecfg "fs" resource type property or attached by mount(1M).
Create and mount the filesystem in the global zone and use LOFS
to mount it into the non-global zone (very safe)
Create the filesystem in the global zone and use zonecfg to mount
the filesystem into the zone as a UFS filesystem (very safe)
Export the device associated with the disk partition to the non-global
zone, create the filesystem in the non-global zone and mount it. Security consideration: If a _block_ device is present in the zone, a malicious user could create a corrupt filesystem image on that device, and mount a filesystem. This might cause the system to panic. The problem is less acute with raw (character) devices. Disk devices should only be placed into a zone that is part of a relatively trusted infrastructure.
Mount a UFS filesystem directly into the non-global zone's directory
structure (allows dynamic modifications to the mount without rebooting
the non-global zone)
See the administration guide for instructions to use these methods. [September 2006]
Q: How can I make a writeable /usr/local in a sparse-root zone?
A: Use one of the methods above, for example:
global# mkdir -p /path/to/some/storage/local/twilight
global# zonecfg -z twilight
zonecfg:twilight> add fs
zonecfg:twilight:fs> set dir=/usr/local
zonecfg:twilight:fs> set special=/path/to/some/storage/local/twilight
zonecfg:twilight:fs> set type=lofs
zonecfg:twilight:fs> end
zonecfg:twilight> commit
zonecfg:twilight> exit
global#
Q: Can I assign an SVM meta-device, or a
Veritas LUN, to a non-global zone?
A: With Solaris 10 1/06, you can directly assign an SVM meta-device into a
non-global zone, using the same method you would with most other devices.
Symantec does not yet support the assignment of a Veritas LUN into a non-global zone. [January 2006]
Q: Can I, and should I, import raw devices into a
non-global zone?
A: The Solaris Zones feature set provides the global zone administrator
with the ability to allow a non-global zone to access a raw device. There
are many situations where this will be the best approach to solve a
problem. There are even situations which require such use.
First, however, it is important to stress that there are usually other
solutions that do not require direct device access. Let's discuss this
first.
One FAQ is "Can I import VxVM devices
into a zone?" Since this is not possible at this time [January 2006],
we look for another solution. If the goal is to make a filesystem
available in the zone, the solution is obvious: create the filesystem
in the global zone, and use LOFS to make the filesystem available
in the zone. On the other hand, if the goal is to make a mirrored
block device available in the zone, another solution must be found.
In any situation, if direct device access is required within a zone,
you must perform careful failure analysis and evaluation of the possible
outcomes of "catastrophic application failure. If the non-global zone
will use COTS software, and will be managed by trustworthy people, then
the risks will be small. Fortunately, in most cases there are also
other solutions which do not use direct device access from a zone.
Here are two extreme examples:
A zone will be created for the purpose of training students on basic Unix
commands. The root account will only be used by the global zone administrator.
The system will be attached to a LAN which is not connected to any other
networks. The instructor needs access to the sound device. There are very few
risks associated with such access - it would be very difficult for the sound
device to suffer a failure, and even if it did it would be unlikely to affect
other zones.
The zone can be given access to this via the zonecfg sub-commands:
global# zonecfg -z zonename
zonecfg:zonename> add device
zonecfg:zonename:device> set match=/dev/sound/*
zonecfg:zonename:device> end
zonecfg:zonename> exit
The zone will have access to sound devices, but will not have access to any
other devices.
A zone will be created for the purpose of teaching students about a
database program that requires access to raw disk partitions. The instructor
knows how to use Unix, but does not have a background in Unix system
administration. Further, the instructor will require use of the root account
to assist students. It is possible that the instructor could make a mistake,
or a malicious student could abuse the raw disk access, leading to a crash of
the kernel. This would also stop all of the other non-global zones, as well
as the global zone. If the other zones are running production software, this
request for raw disk access in a zone should not be fulfilled. Other
solutions should be pursued, such as creating an RBAC role for the instructor
which only gives the necessary privileges to the isntructor's Unix account.
Other examples must be judged by their particulars, e.g. a production database
program which needs raw access. Factors to consider include:
Who will login to the zone? How trustworthy are they?
Is this system protected from unauthorized access by a firewall?
What level of availability is required by applications running in this zone
and in other zones?
For even more information on this topic, see the section "SECURITY AND DATA INTEGRITY" of the man page for sgen(7d).
[September 2005]
Q: Can I share an I/O resource (e.g. NIC, HBA)
between containers?
A: Yes, in fact, that is the default model. Each container is assigned
its own IP address, but usually multiple containers will share one NIC.
Further, multiple zones may be assigned separate filesystems accessed
through one HBA.
Q: Can zones in one computer communicate
via the network?
A: Both
shared-IP and exclusive-IP zones can communicate via the network.
The network traffic for shared-IP zones that communicate between
themselves on the same machine will not
leave the host, whereas network traffic will leave the host when using
exclusive-IP zones.
Full IP-level functionality is available in an exclusive-IP zone. Currently exclusive-IP zones communicate with each other over the
network--no communication local to the system. That communication can
be restriced using IP Filter just as it can for a separate system.
For shared-IP zones in one computer that communicate using IP networking,the following applies:
Inter-zone network latency is extremely small, and bandwidth
is extremely high
Q: How do I modify the network
configuration of a running zone?
A: The ifconfig(1M) command can be used in the global zone to modify a
zone's existing network configuration or to add new logical interfaces
to a zone. Here are some examples that add, and then delete a logical
interface assigned to a zone:
Q: Can IP Multipathing (IPMP) be used with zones?
A: Yes.
Exclusive-IP zones can use IPMP. IPMP is configured the same way in an exclusive-IP zone as it is on
a system not using zones.
For shared-IP zones, IPMP
can be configured in the global zone. Failover of a
network link (e.g. hme0) that is protected by IPMP will bring the
associated logical interfaces (e.g. hme0:3) for the zones over to the
secondary link (e.g. bge0).
For more information, see the section "Using IP Network Multipathing on a Solaris System With Zones Installed" in System Administration Guide: Solaris Containers-Resource Management and Solaris Zones.
[November 2007]
Q: Can IP Filter be used with zones?
A: You have the same IP Filter functionality that you have in the global zone in an exclusive-IP zone. IP Filter is also configured the same way in exclusive-IP zones and the global zone.
For shared-IP zones, the IPFilter features in Solaris 10 can be used to filter traffic
passing between one non-global zone and other computers on the network. This includes the ability to use NAT features, i.e., redirect traffic destined for the global zone to non-global zones.
[November 2007]
Q: Can I prevent a zone from using the network?
A: Yes. A zone does not need a network interface in order to operate. If you don't specify a network interface when you create the zone, it will still boot correctly. If an existing zone has been given access to a network interface, you can use zonecfg(1M) to remove that access, but if the zone is running you must also either re-boot the zone or use ifconfig(1M) to remove access until the next re-boot.
It is also possible to allow a shared-IP zone to access the network, but not communicate with other zones on the same system. One method is to set up a pair of routes using the "-reject" argument to the route(1) command. For example, if one zone has an IP address of <Addr1> and the second zone has an address of <Addr2>, then the following commands will prevent network traffic from passing between the two zones. [July 2006]
Q: Are VLANs supported in zones?
A: Yes. For a shared-IP zone, the VLAN interface must be plumbed in the global zone. LAN and VLAN separation are available in an exclusive-IP
non-global zone.
Q: When I tried to mount a file system into a non-global zone, an error message displayed stating that the mount point was busy. Why?
A: All accesses to entries in lofs mounted file systems map to their
underlying file system. Therefore, if a mount point is made available
in multiple locations via lofs and it is in use in any of those
locations (as a mount point, a current working directory, etc.),
an attempt to mount a file system at that mount point will fail unless
the overlay flag has been specified.
[November 2007]
Q: How can I mount a filesystem into two
or more different zones safely?
A: Create a directory in the global zone, and remount it into each
non-global zone using lofs. This will allow reading and writing from both
zones without corrupting. It's the same mechanism used by the
automounter in certain cases.
Q: How can I create a zone with its own
/usr or root file system (a 'whole root file system')?
A: By default a zone shares /usr and a few other directories with the
global zone. If a zone needs its own separate copy of /usr, et al., you
must tell zonecfg to not use the default configuration. To do this, use
the "-b" option on the "create" sub-command of the zonecfg(2) command.
If you do this, you must specify each existing file system that you do
want to share with this new zone.
Q: How do I configure a default route in a
container?
A: For a shared-IP configuration: All routes, including default routes, must be configured by the global zone administrator. Although a default route cannot be assigned directly to a Container, a default route can be assigned to each subnet. All zones on one subnet will then use the same default route.
For an exclusive-IP configuration: The zone administrator can configure IP on
those data-links with the same flexibility and options as in the global zone. [November 2007]
Q: How can I restrict a zone (or a few
zones) to one NIC (network connector)?
A: Exclusive-IP zones have separate TCP/IP stacks, so the separation reaches
down to the data-link layer. One or more data-link names, which can be a
NIC or a VLAN on a NIC, are assigned to an exclusive-IP zone by the global
administrator. The zone administrator can configure IP on those data-links
with the same options as in the global zone.[November 2007]
Q: How can I restrict a zone (or a few
zones) to one HBA (storage connector)?
Each zone uses
space in at least one disk partition - its root directory and several
others (e.g. /etc) live there. All of these files are part of Solaris.
In addition, each zone can be given access to one or more file systems
and/or one or more raw disks. By planning carefully, you can configure
one zone so that all of its files and devices are accessible through
one HBA, and all of the storage of another zone is accessible through a
different HBA. [August 2005]
Q: Can a non-global zone NFS-mount a file
system that has been shared from its own global zone?
A: No. This may be addressed in the future. However, the filesystem can
be LOFS-mounted into the local zone, and, if necessary, the global zone
can export the same filesystem via NFS so that other computers can also
access those files. [August 2005]
Q: Can a zone's root directory be on a ZFS file
system?
A: A zone's root directory (i.e. it's PATHNAME) can be on a ZFS file
system, but this is not recommended at this time if you plan to upgrade
the system to a future release of Solaris 10. This is because the
software that installs and upgrades Solaris 10 does not yet understand
ZFS, and would not be able to upgrade those zones.
This situation leaves you with three choices:
Do not put zones on ZFS file systems yet
Put zones on ZFS file systems and uninstall them before upgrading
to a new Solaris 10 release
Put zones on ZFS file systems and re-install the system when you
need to use a new Solaris 10 release
Sun is improving the installation software to understand ZFS. A date
for release of this has not been set, but is expected in late 2007 or
early 2008. At that time, a system with zones on ZFS file systems
will be upgradeable.
[April 2007]
Q: Can a zone be an NFS server?
A: A global zone can be an NFS server. A non-global zone cannot be an NFS
server. This issue may be addressed in the future. See RFE
5102011. [August 2005]
Q: Can a zone be a DHCP server?
A: A global zone can be a DHCP server.
Q: Can a zone be an NTP server?
A: Because the NTP server software also sets the time clock, which
a non-global zone cannot be allowed to do, a zone cannot be an NTP
server. (June 2005)
Q: Can a zone be a NIS (aka
yp), NIS+, or LDAP server?
A: Yes, yes, and yes.
Q: Can a zone provide network login
via telnet, rlogin, rsh or ssh?
A: Yes, yes, and yes.
Q: Can a zone be an ftp server?
A: A zone can be an ftp server, but it is not possible to use ftpconfig(1M) to set up a zone to be an anonymous ftp server. This is because ftpconfig attempts to set up certain device special files, and a zone does not have the necessary privileges. [December 2005]
Can a zone run sendmail?
A: Yes.
Can I use X windows in a zone?
A: There are a few different methods to use X windows with zones:
On the system console: at the login screen, you can choose "Remote Host" and enter the hostname of the zone. The X windows login screen should be replaced with an X windows remote login screen.
At the console, logged into the global zone: you can tell X to allow remote connections from the non-global zone, telnet to that zone, and set the appropriate environment variable so that X sessions go to the global zone's X windows session, e.g. "setenv DISPLAY my-global-zone".
At another system, you can login directly to the non-global zone, and perform steps similar to the previous method.
Q: How can I prevent one container from consuming
all of the CPU power?
A: Use the resource management features of Containers. This requires
using assigned CPUs, Resource Pools and/or the Fair Share Scheduler features
and assigning related parameters to each container.
Q: What is the resource granularity for CPU
assignment to a container?
A: Dedicated CPU and Capped CPU: CPU range Resource Pools: Single thread Fair Share Scheduler: Arbitrary. CPU utilization limits are
specified by "shares" and enforced by the Fair Share Scheduler. For
example, CPU limit
assignments could be 1, 1000, 999, resulting in utilization limits of
0.05%, 50%, and (practically speaking) 50%.
Q: How can I limit (cap) the CPU usage of an
application?
A: In Solaris Express, use the capped-cpu resource type.
In Solaris 10 8/07 or Solaris Express, you can use the dedicated-cpu
resource type to create a temporary pool while the zone is running. See Non-Global Zone Configuration (Overview).
Alternatively, you can create a processor set with one or more CPUs and bind it to a
resource pool. Then create a zone and bind it to the same resource
pool. Run the application in that zone. The application will only "see"
that set of processors. For more information, see
Resource Pools (Overview) and Resource Pools (Tasks).
[November 2007]
Q: How can I limit the memory used by a container?
A: You can use the Resource Capping Daemon (rcapd) for all releases.
With Solaris 10 8/07, you can use the capped-memory resource to set limits for physical, swap, and locked memory. Determine values for this resource if you plan to cap memory for the zone by using rcapd from the global zone. The physical property of the capped-memory resource is used by rcapd as the max-rss value for the zone.
Q: Can I dynamically change the quantity of a
resource (CPU, memory,
networkbandwidth)
assigned to a container?
A: To change the number of CPU shares associated with a container
without re-booting it, use the prctl command, e.g.
Q: Can swap space usage be managed?
A: The entire swap partition is treated as a single global resource to
processes running in both global and non-global zones. With Solaris 10
GA, you can't limit the amount of swap used by a zone on a per-zone
basis. You can globally limit the size of the swap-based
filesystems (e.g. /tmp) by using the "size" mount option in the container's /etc/vfstab file, e.g. "size=200m". This allows you to decrease
the effect of many and/or large files created in /tmp.
Starting with Solaris 10 8/07, you can use the resource control, zone.max-swap. (The swap property of the
capped-memory resource is the preferred way to set this control.)
Q: Can I limit the network bandwidth used by a
zone?
A: Yes, use the IPQoS features in Solaris 10. You must manage this from
the global zone for the containers.
Q: Do containers use up alot of CPU power?
A: CPU overhead of containers is hardly
measurable (i.e. <1%) for a few zones or even dozens of zones,
depending somewhat on the applications.
Q: Can the share value for a running
project or zone be changed?
A: Yes. Here is an example:
The prctl utility allows the
examination and modification of the resource controls associated with
an active process, task or project on the system. It allows access to
the basic and privileged limits on the specified entity.
-n specifies the name of the resource
to get or set
-r specifies a replace operation
-v specifies the new value for the resource
-i specifies the owning process, task
or project of the resource.
Q: Can I bind a zone to a pool?
A: Yes. First create the pool, then use zonecfg(1M) to bind a zone to it.
1. Enable resource pools on your system using either svcadm or pooladm -e.
2. Use pooladm -s to create the pool configuration.
3. Use pooladm -c to commit the configuration at /etc/pooladm.conf.
4. Use poolcfg -c to modify the configuration.
Q: Can projects/zones be reassigned
to a different resource pool while they are running?
A: Yes. Here is an example:
poolbind
-p web_app -i zoneid myzone
The poolbind command binds zones,
projects, tasks and processes to a pool.
-p is the name of the pool to bind
-i specifies the process id, zone id, task id or project id to be bound
to the
pool.
Q: Can you move processors between
processor sets while the system is running?
A: Yes you can. Here is the command(s) you would use:
If you don't care which CPUs you move from a processor set the
command would be: poolcfg
-dc "transfer 2 from pset
pset1 to pset2"
which will move any two processors from pset1 to pset2
-d operate directly on the kernel state
-c this signifies the command
If you want to move a specific CPU(s) here is the command: poolcfg
-dc "transfer to pset
pset2 (CPU 0, CPU 1)"
which will move CPUs 0 and 1 to pset2.
Q: How can I prevent one zone from using all
the swap space by filling up /tmp?
A: For manual mounts, use the option "-o size=sz" where sz
is the size limit you want. Ending the size in 'k' means kilobytes,
ending it in 'm' means megabytes. Example: "-o size=500m". This option
can also be added into /etc/vfstab. For more details, view the man
pages for mount_tmpfs(1M) and vfstab(4).
With Solaris 10 8/07, you can use the resource control, zone.max-swap. (The swap property of the
capped-memory resource is the preferred way to set this control.)
Also, note that RFE
1177209 will give the global zone administrator the ability to
control
the amount of swap space used by one zone.
Q: How do I create a zone?
A: First gather some information, then use the Solaris Container Manager GUI or the commands shown below. This is the simplest possible creation of a zone that has network access. You will need this information (example values in parentheses:
Name that you choose for the zone (my-zone)
Hostname that choose for the zone (my-zone)
Name of the directory in the global zone where all of the zone's operating system files will be (/zones/zone_roots/my-zone)
IP address of the zone (10.1.1.1)
Name of the network device that the zone should use (hme0)
Using the sample information in the appropriate commands, which will take about 10 minutes on a small system with a new installation of OpenSolaris or Solaris 10:
global# zonecfg -z my-zone
zonecfg:my-zone> create
zonecfg:my-zone> set zonepath=/zones/zone_roots/my-zone
zonecfg:my-zone> add net
zonecfg:my-zone:net> set address=10.1.1.1
zonecfg:my-zone:net> set physical=hm0
zonecfg:my-zone:net> end
zonecfg:my-zone> commit
zonecfg:my-zone> exit
global# zoneadm -z my-zone install
global# zoneadm -z my-zone boot
Q: Can each container be a different Solaris
patch level, so I can test patches in a "test" container before
applying them to a "production" container?
A: There are two parts to the answer:
1) There is only one kernel running on the system, so all zones must be at the same patch level with respect to the kernel and core system components. Such patches can only be applied from the global zone, and they affect the global and all local zones equally. The KU is an example of such a patch.
2) Middleware such as Java Enterprise System can be patched on a per-zone basis. If the software can be installed in the local zone then it must be patchable from the local zone as well, regardless of the zone type, whole-root or sparse-root.
Q: Is there a way to correlate audit
records from multiple containers?
A: Yes, the global zone sees all audit records. Each non-global zone only
sees its own audit records.
Q: Can I add packages to just the global
zone (for example, SRS netConnect)?
A: Yes, use pgkadd
-G. Note that if the SUNW_PKG_THISZONE package parameter is set to true, you do not have to use the -G option. See packaging and patching chapters
[September 2006]
Q: Can I add a package to one non-global zone
without adding it to the global zone?
A: That depends on the settings used when the package was created. See
the
Packaging sections at docs.sun.com.
Q: What commands don't work, or behave
differently, inside a zone?
A: Most Unix commands and programs work correctly, without alteration
or re-compilation.
However, the implementation of the security isolation boundary
limits the functionality of several system calls and libraries. That, in turn,
limits the functionality of several system commands. In other words,
some Solaris commands behave differently when run inside a zone,
or do not work at all inside a zone.
Q: Do zones boot automatically, or must
I boot each one manually every time the system (re)boots?
A: The zones autoboot property determines whether the zone is booted when the system boots. The global zone adminstrator can set the autoboot property to "true" or "false." The zones service svc:/system/zones:default must also be enabled. [September 2006]
Q: Should I halt a system's zones before
applying patches?
A: There is no need to do this. In fact, the package and patch tools
will perform their operations on all zones that are running, as well as
all zones that are not currently running but are capable of being
booted (e.g. they are at least in the "installed" state). The running
zones are operated on first, and then for each zone that is not running
but can be booted, the zone is booted, the operation is performed, and
the zone is then halted.
Q: Where does a zone's syslog output go?
A: By default the syslog output from a zone goes only into the zone's
syslog
file. If you would like the output to also appear in the global zone's
log
files, configure the non-global zone's loghost to be the global zone.
Q: I removed a device from a zone, but it's
still there. Why, and how do I get rid of it?
A: This is bug 4963368. The current (Feb 2005) workaround is: after
using zonecfg to remove the device, manually remove the corresponding
entry in {ZONEPATH}/dev.
If you're running Solaris Express, this bug is corrected in builds 46
and higher. If you are running Solaris 10, this bug is corrected in Solaris 10 8/07.
Q: How do I upgrade a system with zones installed? Does Live Upgrade work?
A: Information about how to upgrade your Solaris 10 system to a later release if you are running zones is available in the System Administration Guide: Solaris Containers--Resource Management and Solaris Zones, Chapter 27 Upgrading a Solaris 10 System That Has Installed Non-Global Zones.
Limited upgrade for a Solaris Express system that has zones installed began
in SX 7/06. Can only use standard upgrade with limitations and limited
JumpStart keywords.
See the installation documentation.
Full upgrade for a Solaris Express system that has zones installed
began in SX 2/07. No limitations on standard upgrade, no limitations on
JumpStart, and includes Solaris(tm) Live Upgrade. See the installation documentation.
Full upgrade for a Solaris 10 system that has zones installed
began in Solaris 10 8/07. You can use Solaris Live Upgrade, the standard
Solaris interactive installation program, or the custom JumpStart
installation program to upgrade your Solaris system with zones installed.
See the installation documentation. Limited upgrade via standard
upgrade with limitations and limited JumpStart keywords was available in
Solaris 10 11/06.
Solaris Release
Traditional Upgrade w/ Zones
Live Upgrade w/ Zones
Solaris 10 3/05
N/A
N/A
Solaris 10 1/06
Yes
No
Solaris 10 6/06
Yes
No
Solaris 10 11/06
Yes*
No
Solaris 10 8/07
Yes*
Yes
Solaris Express
Yes
Yes
* Note, however, that there are two limitations regarding the process of
upgrading Solaris 10 if there are zones that use ZFS or LOFS. Fixes
for these two issues are under development, or already exist but could
not be integrated into Solaris 10 11/06 in time for release. Note that the LOFS problem has been fixed in Solaris 10 8/07.
Solaris 10 6/06 supports the use of ZFS file systems. It is
possible to install a zone into a ZFS fs, but the installer/upgrader
program does not yet understand ZFS well enough to upgrade zones
that 'live' on a ZFS file system. Because of this, upgrading a system
that has a zone installed on a ZFS file system is not yet supported.
If all non-global zones that are configured with "lofs" fs
resources are mounting directories that exist in the miniroot, the
system can be upgraded from a previous release of Solaris 10 to the
Solaris 10 11/06 release using standard upgrade. For
example, a lofs mounted /opt directory presents no issues for
upgrade.
However, if any of your non-global zones are configured with a
non-standard lofs mount, such as a lofs mounted /usr/local directory,
the following error message is displayed:
The zones upgrade failed and the system needs to be restored
from backup. More details can be found in the file
/var/sadm/install_data/upgrade_log on the upgrade root file
system.
The error message is incorrect: although this error message
states that the system must be restored
from backup, the system is actually fine, and it can be upgraded
successfully using the workaround.
Workaround:
1. Reboot your system with the installed OS.
2. Reconfigure the zones, removing the "fs" resources defined with a
type of "lofs."
3. After removing these resources, upgrade the system to Solaris 10 11/06.
4. Following the upgrade, you can again reconfigure your zones to
restore the additional "fs" resources that you removed.
This problem is being tracked as CR 6454140: "Zones With an "fs" Resource Defined With a Type of "lofs" Cannot Be Upgraded to Solaris 10 11/06" and is also described in the Solaris 10 11/06 Release Notes.
[November 2006]
Q: Are there any special guidelines for using
Live Upgrade with zones?
A:
There are a number of considerations when using
Live Upgrade (LU) on a system with zones installed. It is critical to avoid zone state transitions
during lucreate and lumount operations.
When you lucreate an alternate boot environment (ABE),
if a zone is not
running, then it cannot be booted until the
lucreate has completed.
When you lucreate an ABE, if a zone is running,
it should not be halted or rebooted until
the lucreate has completed.
When an ABE is lumounted, you cannot boot
zones or reboot them, although zones that
were running before the lumount
can continue to run.
Because a non-global zone can
be controlled by a non-global zone administrator as well as
the global zone administrator, it is
best to have all zones halted during
lucreate or lumount.
It is important to note that when LU operations are underway,
non-global zone administrator involvement is critical. The upgrade affects their work as administrators, and
they will be dealing with the changes that occur as a result
of the upgrade. They should make sure that any local packages
are stable throughout the sequence, handle any post-upgrade tasks
(such as configuration file tweaking), and generally schedule around the
system outage.
Here is an example of a problem that could occur if these guidelines are not followed.
If this sequence of actions takes
place:
In global zone: lucreate -n new
In non-global zone: pkgadd FooBar
In global zone: luupgrade -n new, luactivate -n new,
init 6
When the system comes back up, the non-global zone users will notice
that they no longer have the FooBar feature added by the package.
[January 2008]
Q: Can I configure my zones on a ZFS filesystem?
A: Solaris 10 Update Release:
It is possible to install a zone on a ZFS file system. However,
at this time, we do not recommend putting the zonepath of a non-global
zone on ZFS due to possible problems with upgrading the system to a later
Solaris 10 update release. Support for zonepaths on ZFS is under development. [September 2006]
Q: What is the default networking service configuration of a non-global zone when it is installed?
A: On Solaris 10 systems, the traditional open configuration is installed. On SX systems, the limited networking configuration is installed.
You can switch the zone to either networking configuration by using the netservices command, or enable and disable specific services by using SMF commands. [September 2006]
Q: Can I access one zone from
another zone?
A: Only through IP connections, e.g. telnet, rlogin.
Q: Can I 'su' from one zone to another?
A: No, this would violate the security implementation of zones. In this
context, think of zones as separate computers - you can't 'su' from one
Unix computer to another.
You can use the zlogin(1)
command to login to a non-global zone from the global zone. You must
have all privileges(5)
to use zlogin. Q: Can I prevent the root account
in one zone from affecting other zones?
A: Because each container has its own namespace, each container has its
own root account. Each zone's root account is unable to access
other containers in any way.
Q: Can programs running in one zone change the
operation of programs running in another container?
A: A great deal of design work was done to prevent containers from
affecting each other. By default it is very difficult for one local
zone to affect another zone, but it is possible. It is also easy for
the global zone administer to configure containers unsafely. Consider
these factors:
First, there are no known methods for one user (even root) in one
local zone to 'break into' another zone (global or non-global).
However, a modern computer has many resources, some of them real, some
virtual. Denial of Service attacks often attempt to use all of the
instances of a virtual resource. One early attack on Unix systems was
creating so many processes that all of the PIDs were in use, preventing
the creation of new processes. There are now methods to prevent those
attacks, and those methods automatically apply, or have been applied
to, zones. In some cases the method of prevention includes the manual
use of Solaris features, e.g. projects.
By default it is difficult to disrupt operation of zones.
However, the global zone administrator can make it easier for a non-global
zone user to impact operation of one or more other zones, even the
global zone. Try to avoid assigning disk devices directly to non-global
zones: the root user of that zone might be able to take advantage of
this to cause a SCSI bus reset or even panic the kernel. Also, avoid
assigning the same device or file system to multiple
zones unless needed to achieve a specific goal. If that is necessary,
ensure that all of the software in those two zones will obey a
synchronization mechanism when using the device or file system.
Q: How do I prevent a 'fork bomb' from affecting all of the zones?
A: A 'fork bomb' is a process which creates (forks) as many child processes as possible, attempting to use up all of the virtual memory or PIDs in a system, resulting in a Denial of Service to other users. If you would like to prevent someone from doing this in a non-global zone, add this to a zone's configuration, using zonecfg(1M):
add rctl
set name=zone.max-lwps
add value (priv=privileged,limit=1000,action=deny)
end
That will prevent a zone's processes from having a total of more than 1000 LWPs simultaneously. [December 2005]
Q: Can Oracle use shared memory in a Container?
A: Because we keep improving Containers, there are two different answers to this question.
Solaris 10 11/06 and later: Yes, Oracle can use ISM or DISM in a Container.
To enable the use of DISM, the global zone administrator must add the
privilege "proc_lock_memory" to the Container. To do this, use zonecfg(1M) to add the line
set limitpriv=default,proc_lock_memory
to the Container's configuration.[January 2007]
Solaris 10, Releases 3/05, 1/06, 6/06: Yes, however Oracle can only use ISM (Intimate Shared Memory) in a zone. It cannot use DISM (Dynamic ISM) in a zone. This is a side-effect of the implementation of the security boundary which protects zones from each other. [June 2006]
Q: Can I use the Solaris 10 FSS (Fair Share Scheduler) with Oracle in a Solaris Container?
A: There are currently (June 2006) two distinct concerns regarding the use of FSS in a Container when running Oracle databases:
In testing - Oracle processes use internal methods to prioritize themselves to improve inefficiency. It is possible that these methods might not work well in conjunction with the Solaris FSS. Although there are no known problems with non-RAC configurations, Sun and Oracle are testing this type of configuration to discover any negative interactions. This testing should be completed soon.
It is not possible to use the Solaris FSS with Oracle RAC in a Container. A Solaris patch is being tested that fixes this problem.
Cost: zones are a feature of the operating system. There is no extra charge for using them.
Integration: Zones are integrated into the operating system, providing seamless functionality and a smooth upgrade path.
Portability: Zones are not tied to any one hardware platform. As a device-independent feature set of OpenSolaris, their functionality is exactly the same on all hardware to which OpenSolaris has been ported.
Observability: The Global Zone has visibility into all activity in all zones, including viewing process and network activity, system-wide accounting and auditing, etc. This makes it possible to find performance problems and resolve inter-zone conflicts, both of which are extremely difficult problems on most other SV solutions. It is even possible to re-host applications typically found on different systems (e.g. web server and app server) on different zones in the same system, and then use DTrace to analyze their interactions.
Manageability: You can manage all of the zones on one system as one collection, rather than as separate servers. This includes adding packages and patches once per system, not once per zone.
Sun Dynamic System Domains
Q: Are containers like VMware?
A: They are only vaguely similar. Both technologies are very useful for
consolidating servers. However, the basic model is different:
Containers form isolated application environments that share one OS
instance, while VMware hosts multiple OS instances. The differences
also include:
Containers are only available for Solaris 10 and SX Nevada. VMware supports
Solaris, Microsoft Windows and Linux clients, simultaneously.
VMware uses a great deal of CPU capacity managing the multiple
environments. CPU overhead of containers is hardly
measurable (typically <1%) for a few zones or even dozens of zones,
depending somewhat on the applications.
Containers do not have any financial cost beyond Solaris license
and/or support costs. VMware for production environments costs thousands
of dollars, and a license is necessary for each Windows or RH instance
hosted on top of VMware.
Q: Are containers like HP vPars or nPars?
A: Containers are not similar to either except in purpose: server
consolidation. However, the differences include:
HP nPars and Sun's Dynamic System Domains are similar in that
both provide complete isolation of data, applications, and programs. A
complete comparison of Domains and nPars is outside the scope of this
document.
vPars are HP's "soft" partitioning technology. vPars and
Containers each enable multiple applications to co-exist in a set of
hardware resources with some degree of isolation.
Each vPar is its own instance of an operating system, and must be
managed separately. Each container is a virtual instance of Solaris,
but there is only one copy of Solaris to maintain.
Containers are only available for Solaris 10. vPars only support
HP-UX (versions ??).
All vPars share the same root password. Someone who gains root
access in one vPar can do anything to any vPar. Conversely, each
Solaris Container has its own namespace, including its own root
account. Someone who gains root access in one container can damage that
container (unless privileges have been removed) but cannot cause any
damage to any other container, including the global container. However,
keep in mind that if a vPar or Container is configured poorly, the
potential for inter-partition damage is increased.
Q: Are containers like IBM Micro-Partitions?
A: They are only vaguely similar. Both technologies are very useful for
consolidating servers. However, the differences include:
Containers are only available for Solaris 10. MicroPars only
support
AIX 5.3, RH.
Each MicroPartition requires a separate license to run an
operating system. There is a cost associated with each AIX license.
Containers have almost no overhead, i.e. running 10 applications
in 10 Containers is only slightly less efficient than running those 10
applications in a non-zoned system. The difference is typically <1%.
MicroPartitions are inefficient and have high overhead. According to
IBM documentation, 10 MicroPartitions can have a compute overhead of
35%, in addition
to the application workload.
Containers and MicroPartitions can share I/O resources, but the
implementation is different. MicroPars that want to share an I/O
connector must use an LPAR dedicated to the multiplexing of I/O. This
LPAR has extra costs associated with it: one or more additional Power
processors, another AIX license, etc. [Updated July 2005]
Q: Are containers like Linux vServers?
A: The basic model used to implement the Solaris 10 Containers feature
set and the Linux vServers project are fairly similar. However, the
implementation is different. (More coming soon!) [Updated August 2005]
Q: I created a zone and booted it, but it doesn't work. What should I do?
A: The most common problem is that the zone doesn't have its system identification information yet. You can determine if this is the problem by running "ps -fz " in the global zone. If the output only shows zsched, init, and a (3-6) processes related to SMF (/lib/svc/..., /usr/sbin/svccfg) then system identification is not complete. To complete this, attach to the zone's console by running "zlogin -C " in the global zone, pressing once, and following the instructions. [March 2006]
Q: I added some privileges to a user in a zone, and now the user can't login. What should I do?
A: This resulted from a bug that was fixed in Solaris Express 4/06. It will be corrected in Solaris 10 11/06 as well.
Updated information on privileges and zones has been added to the System Administration Guide: Solaris Containers--Resource Management and Solaris Zones. See documentation for a list of the Solaris privileges and the status of each privilege with
respect to zones. To alter privileges in zones, use the limitpriv property in zonecfg. [September 2006]
Q: I tried to upgrade to Solaris 10 11/06 and it told me the upgrade failed and I need to restore from backup. Now what?
A: Although this error message states that the system must be restored from backup, the system is actually fine, and it can be upgraded successfully. See "How do I upgrade a system with zones installed? Does Live Upgrade work?" for more information and a workaround you can use to upgrade your system.