OpenSolaris

1. Project: COMSTAR: Common Multiprotocol SCSI Target
   1. Events
   2. News
   3. Blogs
   4. Discussions
   5. Leaders
   6. Observers
   7. Files
   8. Source Code
   9. COMSTAR and Linux Multipathing
   10. Demos and Videos
   11. Documentation
       1. COMSTAR Admin Guide
       2. Specs and Man Pages
       3. Release Notes
       4. COMSTAR FAQs
   12. Using the mptt SAS target driver in COMSTAR
   13. SCSI Block Device Pass Through Provider

OpenSolaris Project: COMSTAR: Common Multiprotocol SCSI Target

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Introduction to COMSTAR

COMSTAR is a software framework that enables you to turn any OpenSolaris host into a SCSI target that can be accessed over the network by initiator hosts. COMSTAR breaks down the huge task of handling a SCSI target subsystem into independent functional modules. These modules are then glued together by the SCSI Target Mode Framework (STMF).

In following illustration, the OpenSolaris target host is configured as a storage array using COMSTAR. The initiator hosts can be any platform: Solaris 10, Windows, Linux, VMware ESX, etc.

The modules implementing functionality at SCSI level (disk, tape, etc.) do not need to interact directly with the underlying transport. Likewise, the modules implementing the transport protocol (Fibre Channel, iSCSI etc.) are not aware of the SCSI level functionality inherent in the packets they are transporting. The framework compartmentalizes the execution and cleanup of SCSI commands and the associated resources. This simplifies the task of writing SCSI or transport modules.

COMSTAR features include:

• Extensive LUN Masking and mapping functions
• Multipathing across different transport protocols
• Multiple parallel transfers per SCSI command
• Scalable design
• Compatible with generic HBAs

The port providers implement target transports, such as Fibre Channel. The logical unit (LU) providers implement SCSI logical units, such as disk, tape, and the like.

How to Get COMSTAR

COMSTAR is integrated into the latest Solaris Express Community Edition (SXCE) starting with SXCE build 90. You can get the latest SXCE from the OpenSolaris web site downloads page. COMSTAR is available by default after you install the latest SXCE (end user support or higher metacluster).

COMSTAR is also available in the OpenSolaris distribution starting with the 2009.06 release. As a convenience, you can install all the appropriate IPS packages by pkg install storage-server.

Related Projects

• iSCSI Extensions for Remote DMA (iSER) will provide iSCSI support for COMSTAR
• Fibre Channel over Ethernet will provide FCoE support under COMSTAR
• SRPT provides SRP Target support under COMSTAR

Blogs

danmas - Multipathing for Tape

Jul 2, 6:24 AM

It was a dark and stormy night, the back up windows opened and shut with the regularity of a 90 year old pensioner's clacking of teeth as he snored with the flem filled nervousness of old age and ...

mac - So you want to build a storage server...

Jun 18, 3:17 PM

You have lots of company. Storage Servers have been around since the days when Sun first put NFS on their workstations. Administrators would load up one workstation with disks and share it with the ...

danmas - Fun in the Sun

Jun 17, 8:35 AM

Deirdré Straughan , Community-Monger and Videoblogger Extraordinaire came to work with me about 18 months ago. She now works in a different organization doing fun things that rightly play to her ...

mac - XAM Java Binding Overview

Jun 16, 9:32 AM

This article was originaly posted to the Royal Jelly blog: http://weblogs.java.net/blog/macsun/ The eXtensible Access Method ( XAM ) is new kind of storage interface for storage devices that can ...

Sumit Gupta - COMSTAR + ZFS Demo is now online

Jun 14, 7:05 PM

Here is a demo on how to take a machine running Solaris and convert it into a Fibre Channel Array using COMSTAR and ZFS. The demo covers all the steps starting right after a fresh install of the OS ...