An HP-UX system can fail to boot after installing Storage Foundation 5.0.1 Rolling Patch 2 or 5.0 Rolling Patch 8 when using SAS (Serial Attached SCSI) disks/luns as the boot device
Article ID: 100003926
Updated On:
Description
# kctune -v vol_maxspecialioTunable vol_maxspecialioDescription Maximum size of a VxVM I/O operation issued by an ioctl call (kBytes)Module volCurrent Value 256 [Default] <<<<<
Set the values to the current ones in order to override the default setting ( [Default] entry from the Current Value field):
# kctune -h vol_maxspecialio=256* The requested changes have been saved, and will take effect atnext boot.Tunable Value Expressionvol_maxspecialio (now) 256 Default(next boot) 256 256
After rebooting kctune will show the same values in use, but they will no longer be the default. Therefore application of the patch will not override them.
Once kctune show non-default values in use, patch 5.0.1 RP2 or 5.0 RP8 installation can be performed.
It is intended at a later patch level to revert the defaults back to 256KB so this issue is no longer seen.
Set the values to the current ones in order to override the default setting ( [Default] entry from the Current Value field):
# kctune -h vol_maxspecialio=256* The requested changes have been saved, and will take effect atnext boot.Tunable Value Expressionvol_maxspecialio (now) 256 Default(next boot) 256 256
After rebooting kctune will show the same values in use, but they will no longer be the default. Therefore application of the patch will not override them.
Once kctune show non-default values in use, patch 5.0.1 RP2 or 5.0 RP8 installation can be performed.
It is intended at a later patch level to revert the defaults back to 256KB so this issue is no longer seen.
Cause
With the Storage Foundation 5.0.1 RP2 and 5.0 RP8 the value of the VxVM kernel tunable parameter vol_maxspecialio has been changed from 256KB to 1MB.
vol_maxspecialio is bound by the scsimgr (SCSI Manager) global attribute escsi_maxphys, which is the maximum I/O size allowed by the SCSI subsystem.
Certain Serial Attached SCSI (SAS) controller drivers (for example the p410i) on some HP Blade systems limit the maximum I/O size to 256KB. By setting vol_maxspecialio to a value greater than that of escsi_maxphys causes vxconfigd to not be able to read the configuration copy from these SAS disks attached to those controllers resulting in a DiskGroup import failure. If the controller is managing the disk that is the rootdisk, the system will not come up.
Resolution
The patches mentioned adjusts the default values from 256KB to 1MB. If the value in use is not default, then the patch will not effect these attribute settings.
Check If the the values of vol_maxio and vol_maxspecialio are set to their defaults, as reported by the kctune output below:
Issue/Introduction
VxVM vxconfigd ERROR V-5-1-569 Disk group rootdg, Disk c#t#d#s2: Cannot auto-import group:
Disk group has no valid configuration copies
