HP 3000 Manuals HP 3000 Manuals
Mirrored Disk/iX Enhancements
by Rakesh Patel and Linda Runyan
Commercial Systems Division
With this release of MPE/iX, Mirrored Disk/iX has been enhanced to
distinguish between a source volume read error, a source volume hard
error, and a destination volume error during a disk repair.
DISK FAILURE DURING A REPAIR OPERATION
A repair operation involves two disk drives, they are called the repair
source (REPAIR-SRCE) and the repair destination (REPAIR-DEST) disks.
Either disk could fail during a repair operation.
If the source disk fails, then the system behaves as if there were no
mirroring present. This failure is nonrecoverable.
If a read error is encountered on the source disk during the repair
operation, then the condition is recoverable.
Source Disk Error During a Repair
If a read error occurs on a repair source disk during the repair
operation, then the repair destination disk is marked DISABLED and the
repair source disk is marked REPAIR-ERR.
For example, if a source read error occurs on LDEV 32 (REPAIR-SRCE)
during the repair process, then the screen shows that LDEV 33, which was
in the REPAIR-DEST state, is now in the DISABLED state and LDEV 32
(REPAIR-SRCE) is now in the REPAIR-ERR state as shown in the following
example:
:VOLUTIL
Mirvutil A.00.00, (C) Hewlett-Packard Co. 1990.
All Rights Reserved.
volutil:SHOWSET PROD_SET MIRROR
Volume Name Vol Status Mirr Status Ldev Mirr ldev
- - - - - - - - - - - - - - - - - - - - - - - - - -
MEMBER1 MASTER NORMAL 30 31
MEMBER1 MASTER NORMAL 31 30
MEMBER2 MEMBER REPAIR-ERR 32 33
MEMBER2 MEMBER DISABLED 33 32
The repair process has stopped and the following repeating message is
displayed:
99:99/99/READ ERROR ENCOUNTERED ON MIRRORED REPAIR SOURCE LDEV 32
Destination Disk Failure During a Repair
If the repair destination disk fails, then the system behaves as if there
were mirroring and one of the disks fail. That is, the destination drive
is marked DISABLED and the source drive is marked NON-MIRROR.
For example, if the repair destination disk (LDEV 33 (REPAIR-DEST)) fails
during the repair process, then the screen shows that LDEV 33 is now in
the DISABLED state and LDEV 32 (REPAIR-SRCE) is now in the NON-MIRROR
state as shown in the following example:
:VOLUTIL
Mirvutil A.00.00, (C) Hewlett-Packard Co. 1990.
All Rights Reserved.
volutil:SHOWSET PROD_SET MIRROR
Volume Name Vol Status Mirr Status Ldev Mirr ldev
- - - - - - - - - - - - - - - - - - - - - - - - - -
MEMBER1 MASTER NORMAL 30 31
MEMBER1 MASTER NORMAL 31 30
MEMBER2 MEMBER NON-MIRROR 32 33
MEMBER2 MEMBER DISABLED 33 32
Note that in both of the above cases the destination disk drive was
marked DISABLED.
WHAT TO DO IF A DRIVE FAILS DURING THE REPAIR OPERATION
Whenever there is an unexpected failure that necessitates a rebooting of
the system, or when a split-volume set is joined into a mirrored volume
set, all mirrored pairs undergo a repair process. This is necessary to
guarantee the consistency of the mirrored disks. During the repair
operation, one disk is copied to the other (REPAIR-SRCE to REPAIR-DEST).
If the Source Disk Fails
If the source disk of a staged or repairing pair becomes unresponsive
(for example, due to a loss of power), the system behaves just as if
there were no mirroring present. This is a recoverable condition; the IO
waits for the power to be restored and continues.
If the source disk of a staged or repairing pair suffers a hard error,
the system behaves just as if there were no mirroring present. This is a
nonrecoverable error and all files must be restored from tape.
If the repair operation encounters a read error on the source disk, the
disk drive is not considered to have failed, therefore it is recoverable.
The repair operation stops, the source disk is marked REPAIR-ERR, the
destination disk is marked DISABLED, and a repeating error message is
displayed. Run diagnostics on the source disk drive to identify any bad
sectors, then run REPLACEMIRRVOL again.
If the Destination Disk Fails If the destination disk of a repairing
volume pair becomes unresponsive or suffers a hard error, it is marked
DISABLED.
If a destination disk of a staged volume pair becomes unresponsive after
being staged, but before transitioning to be repaired, it is marked
DISABLED at repair time.