Flashes (Alerts)
Abstract
Enabling SCSI-3 Persistent Reserve feature in the storage device involves a trial attempt to reserve and unreserve target disks in exclusive mode by RSCT and GPFS during DB2 instance setup. If this step succeeds, relevant attributes of the target disks will be altered to reflect the SCSI-3 PR enablement. This step can fail if the target disks contain stale reservation bits from previous use. This document provides the pre-DB2 instance setup steps on the target disks to clear any pre-exising reservation or unexpected bits to ensure a smooth DB2 instance setup.
Content
Before creating a pureScale instance:
Prior to creating a pureScale instance, it is recommended that the disk attribute, reserve_policy, be set to "no_reserve". This recommendation applies to all supported shared storage devices, device drivers (i.e. SDDPCM and MPIO) and disk types (i.e., RSCT tiebreaker disks and other GPFS NSDs).
After creating a pureScale instance:
Once db2icrt has been run and the pureScale instance has been created, some of these attributes are updated by RSCT and GPFS as they try to open the device in the mode specified.
- For the RSCT tiebreaker disk, the algorithm value is set to "fail_over" and timeout_policy value (if the attribute exists) is set to "retry_path"
- If the disk has SCSI-3 PR enabled, then reserve_policy value is set to "PR_exclusive"
- If the disk has SCSI-2 enabled, then reserve_policy value is set to "single_path"
- For the GPFS NSDs (including the GPFS tiebreaker disk if the disk quorum is used), the recommended value for algorithm is "fail_over" or "load_balance" and for timeout_policy is "retry_path"
- If the disk has SCSI-3 PR enabled, the reserve_policy value is set to "PR_shared"
- If the disk does not have SCSI-3 PR enabled, the reserve_policy value (if the attribute exists) is set to "no_reserve"
Note:
- All values mentioned above for algorithm, reserve_policy, and timeout_policy have been validated by IBM. Other values may not produce the behavior expected by DB2 pureScale.
- Specification for SDDPCM device driver only:
For the SDDPCM device driver, if algorithm is set to fail_over, the timeout_policy attribute must be set to retry_path. For more information, see http://www-01.ibm.com/support/docview.wss?&uid=ssg1S1004072.
Was this topic helpful?
Document Information
More support for:
Db2 for Linux, UNIX and Windows
Software version:
10.1, 10.5, 11.1
Operating system(s):
AIX
Document number:
282883
Modified date:
25 September 2022
UID
swg21985792