VMDg resources do not fail over when a cluster node faults or reboots in Veritas Storage Foundation HA for Windows or Veritas Storage Foundation for Windows - Option for Microsoft Cluster Service (MSCS)

Article:TECH50503  |  Created: 2007-01-18  |  Updated: 2010-01-17  |  Article URL http://www.symantec.com/docs/TECH50503
Article Type
Technical Solution


Environment

Issue



VMDg resources do not fail over when a cluster node faults or reboots in Veritas Storage Foundation HA for Windows or Veritas Storage Foundation for Windows - Option for Microsoft Cluster Service (MSCS)

Solution



Description

If a node faults or reboots, another node in the cluster may attempt to issue SCSI "break reservation" commands to each of the disks as it attempts to gain control. In some cases, the Microsoft SCSIport.sys translates these "break reservation" commands into "reset SCSI bus." This causes the SCSI bus to be reset many times in a very short time frame, preventing the cluster from regaining control of the disks.

  • If a StorPort driver is being used, the value of "UseBusReset" should be 0. This is the default setting.
  • If a StorPort driver is not being used, the value of "UseBusReset" should be 1.

Solution

A registry key can be modified to change the behavior of the cluster. This prevents nodes from attempting to issue "break reservation" requests to each disk and forces them to issue a single "reset SCSI bus" command instead. In the event of a faulted node or a reboot, the existing SCSI reservations that were issued by the faulted node will still be broken by a single "reset SCSI bus," allowing another node to gain control of the shared disks.

Note: A "reset SCSI bus" command will break the SCSI reservations for all devices on the bus. Symantec strongly recommends that shared storage be connected to HBAs that are not used by other devices, such as tape libraries.

To resolve this issue, perform the following steps:

WARNING: Incorrect use of the Windows registry editor may prevent the operating system from functioning properly. Great care should be taken when making changes to a Windows registry. Registry modifications should only be carried-out by persons experienced in the use of the registry editor application. It is recommended that a complete backup of the registry and workstation be made prior to making any registry changes.

1. Open Regedit
2. Locate the following registry key:

HKEY_LOCAL_MACHINE\SOFTWARE\VERITAS\VxSvc\CurrentVersion\VolumeManager\UseBusReset

3. Change the value of UseBusReset to a REG_DWORD value of 1

Note: This change takes effect immediately. Neither a reboot nor restarting any services is required.

Supplemental Materials

SourceETrack
Value774442
DescriptionVMDg cannot failover after a node is restarted

SourceETrack
Value499038
DescriptionFailovers do not work when they crash the first node if the preferred path has failed


Legacy ID



287024


Article URL http://www.symantec.com/docs/TECH50503


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