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Bug 513072

Summary:	Fence_scsi and SAN fence limitations
Product:	Red Hat Enterprise Linux 5	Reporter:	Paul Kennedy <pkennedy>
Component:	doc-Cluster_Administration	Assignee:	Steven J. Levine <slevine>
Status:	CLOSED NOTABUG	QA Contact:	Content Services Development <ecs-dev-list>
Severity:	high	Docs Contact:
Priority:	high
Version:	5.4	CC:	adstrong, cluster-maint, mhideo, pkennedy, rohara, sghosh, slevine
Target Milestone:	rc	Keywords:	Documentation
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	Bug Fix
Doc Text:		Story Points:	---
Clone Of:	509204	Environment:
Last Closed:	2009-09-03 15:59:55 UTC	Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:	509204
Bug Blocks:

Comment 1 Paul Kennedy 2009-07-21 20:51:48 UTC

This bug addresses a wider range of situations than the original one. Refer to comments by rohara:

"...the 2-node limitation is not specific to fence_scsi. It is a limitation for all SAN fencing agents. In the future it is probably worthwhile to document this, list the SAN fencing agents that are subject to this limitation, etc. In my opinion, specifically noting that fence_scsi does not work in a 2-node cluster implies that all other fence agents that have that limitation will have the same specific note in the documentation."

Comment 2 Steven J. Levine 2009-07-22 16:05:18 UTC

To rohara:

I'm looking to verify the list of SAN fencing agents that do not support two-node clusters.

These are the fencing agents I know about that seem to use SAN devices for fencing:

Egenera SAN Controller
McData SAN Switch
QLogic SANBox2 Switch
Vixel SAN Switch

Is that the full list, or are any of the other supported fencing agents SAN devices?

Thanks,

-Steven

Comment 3 Steven J. Levine 2009-08-11 20:36:22 UTC

For RHEL 5.4, I have added the following note to the Section on Configuring Fence Devices and to the Appendix on Fence Device Parameters:

Note:

* Use of SCSI persistent reservations as a fence
  method is supported with the following limitations:

* SCSI fencing is not supported in a two-node cluster.
 
* When using SCSI fencing, all nodes in the cluster
  must register with the same devices so that
  each node can remove another node's registration
  key from all the devices it is registered with.
  
* Devices used for the cluster volumes should be a complete LUN,
  not partitions. SCSI persistent reservations work on
  an entire LUN, meaning that access is controlled to each
  LUN, not individual partitions.

* SCSI fencing cannot be used in conjunction with qdisk.
  
Documentation on the limitations of using other SAN-based fence devices
will be added to this document in later releases after testing of what
is and isn't supported, in conjunction with updates to the fence_X
man pages for those devices.

The note on SCSI limitations will be in the RHEL 5.4 version of this document.

Comment 4 Steven J. Levine 2009-09-03 15:59:55 UTC

With the release of RHEL 5.4 I'm closing this bug.