The SCSI-3 EARO and WERO persistent reservation types are supported on CLARiiON arrays, but with these limitations regarding Asymmetric Logical Unit Access (ALUA) and failovermodes:
SCSI-3 reservations have been supported with failovermode 1 (passive-not-ready) since failovermodes were introduced with FC4700 CLARiiON arrays.
FLARE 26 introduced ALUA (failovermode 4).
FLARE 26 does NOT support SCSI-2 reservations with ALUA - Any SCSI-2 reservation command on an ALUA initiator will fail with a check condition from the CLARiiON array. FLARE 26 does support SCSI-3 reservations in ALUA failovermode.
FLARE 28.5 patch 704 or later added support for SCSI-2 reservations in ALUA failovermode for CX4 systems and included support for VMware vSphere in ALUA mode. Like earlier revisions, SCSI-3 reservations are still supported with these FLARE revisions.
SCSI persistent reservations are supported on AX4 Series arrays. AX4-5 supports both SCSI-2 and SCSI-3 reservations, but the AX4-5 does not support the ALUA (failovemode=4) mode.
EARO and WERO are persistent reservation types defined as follows:
Shared-read (sr) - 0x00 - Allow read sharing with other initiators to the specified extent.
Write-exclusive (wexc) - 0x01- Inhibit read operations from all initiators to the specified extent.
Read-exclusive (rexc) - 0x02 - Inhibit writes operations from all initiators to specified extent.
Exclusive - 0x03 - Don't allow access from any other initiator to the specified extent.
Shared - 0x04 - Shared reads and writes permitted.
SCSI-3 Persistent Reservations (SCSI-3 PR) are required for I/O fencing and resolve the issues of using SCSI reservations in a clustered SAN environment. SCSI-3 PR enables access for multiple nodes to a device and simultaneously blocks access for other nodes.
SCSI-3 reservations are persistent across SCSI bus resets and support multiple paths from a host to a disk. In contrast, only one host can use SCSI-2 reservations with one path. If the need arises to block access to a device because of data integrity concerns, only one host and one path remain active. The requirements for larger clusters, with multiple nodes reading and writing to storage in a controlled manner, make SCSI-2 reservations obsolete.
SCSI-3 PR uses a concept of registration and reservation. Each system registers its own "key" with a SCSI-3 device. Multiple systems registering keys form a membership and establish a reservation, typically set to "Write Exclusive Registrants Only." The WERO setting enables only registered systems to perform write operations. For a given disk, only one reservation can exist amidst numerous registrations.
With SCSI-3 PR technology, blocking write access is as simple as removing a registration from a device. Only registered members can "eject" the registration of another member. A member wishing to eject another member issues a "preempt and abort" command. Ejecting a node is final and atomic; an ejected node cannot eject another node. In VCS, a node registers the same key for all paths to the device. A single preempt and abort command ejects a node from all paths to the storage device.
Roger_Wu
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2012年11月15日 00:00
是支持的，Primus KB: emc106122有说明：
The SCSI-3 EARO and WERO persistent reservation types are supported on CLARiiON arrays, but with these limitations regarding Asymmetric Logical Unit Access (ALUA) and failovermodes:
SCSI persistent reservations are supported on AX4 Series arrays. AX4-5 supports both SCSI-2 and SCSI-3 reservations, but the AX4-5 does not support the ALUA (failovemode=4) mode.
EARO and WERO are persistent reservation types defined as follows:
yanzs
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2 Intern
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2012年11月15日 07:00
hi，能不能借此机会介绍一下scsi-3 PR，谢谢！！
zhuzhu281306
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2012年11月17日 05:00
CX支持SCSI-3还有限制条件？
zhuzhu281306
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2012年11月17日 05:00
楼主是在做什么测试吗？
为什么需要用到SCSI-3呢
Roger_Wu
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2012年11月18日 17:00
很多群集的系统或应用会要求存储支持SCSI-3 PR，楼主可能准备搭Windows 2008 Cluster或Red Hat Cluster之类的群集。
可以参考下SCSI-3 PR的技术细节，总之就是一组SCSI命令集，用在多个系统访问一个共享存储的时候协调之用。
SCSI-3 persistent reservations
SCSI-3 Persistent Reservations (SCSI-3 PR) are required for I/O fencing and resolve the issues of using SCSI reservations in a clustered SAN environment. SCSI-3 PR enables access for multiple nodes to a device and simultaneously blocks access for other nodes.
SCSI-3 reservations are persistent across SCSI bus resets and support multiple paths from a host to a disk. In contrast, only one host can use SCSI-2 reservations with one path. If the need arises to block access to a device because of data integrity concerns, only one host and one path remain active. The requirements for larger clusters, with multiple nodes reading and writing to storage in a controlled manner, make SCSI-2 reservations obsolete.
SCSI-3 PR uses a concept of registration and reservation. Each system registers its own "key" with a SCSI-3 device. Multiple systems registering keys form a membership and establish a reservation, typically set to "Write Exclusive Registrants Only." The WERO setting enables only registered systems to perform write operations. For a given disk, only one reservation can exist amidst numerous registrations.
With SCSI-3 PR technology, blocking write access is as simple as removing a registration from a device. Only registered members can "eject" the registration of another member. A member wishing to eject another member issues a "preempt and abort" command. Ejecting a node is final and atomic; an ejected node cannot eject another node. In VCS, a node registers the same key for all paths to the device. A single preempt and abort command ejects a node from all paths to the storage device.