mmchcarrier command

Allows IBM Storage Scale RAID pdisks to be physically removed and replaced.

Synopsis

mmchcarrier RecoveryGroupName --release
                {[--pdisk "Pdisk[;Pdisk]" [--location "Location[;Location]"]}
                [--force-release] [--force-rg]

mmchcarrier RecoveryGroupName --resume
                {[--pdisk "Pdisk[;Pdisk]" [--location "Location[;Location]"]}
                [--force-rg]

mmchcarrier RecoveryGroupName --replace
                {[--pdisk "Pdisk[;Pdisk]" [--location "Location[;Location]"]}
                [-v {yes|no}] [--force-fru] [--force-rg] [--nsd-version {1|2}]

Availability

Available on all IBM Storage Scale editions.

Description

The mmchcarrier command is used to control disk carriers and replace failed pdisks.

Replacing a pdisk requires the following three steps:

Run the mmchcarrier --release command to prepare the carrier for removal.
The mmchcarrier --release command suspends I/O to all disks in the carrier, turns off power to the disks, illuminates identify lights on the carrier, and unlocks the carrier latch (if applicable).
Remove the carrier from the disk drawer, replace the failed disk or disks with new disks, and reinsert the carrier into the disk drawer.
Run the mmchcarrier --replace command to complete the replacement.
The mmchcarrier --replace command powers on the disks, verifies that the new disks have been installed, resumes I/O, and begins the rebuilding and rebalancing process onto the new disks.

Note: New disks will take the name of the replaced pdisks. In the event that replaced pdisks have not completely drained, they will be given a temporary name consisting of the old pdisk name with a suffix of the form #nnnn. The temporary pdisk will have the adminDrain pdisk state flag set and will be deleted once drained. For example, a pdisk named p25 will receive a temporary name similar to p25#0010 when the adminDrain state flag is set. This allows the new disk that is replacing it to be named p25 immediately rather than waiting for the old disk to be completely drained and deleted. Until the draining and deleting process completes, both the new pdisk p25 and the old pdisk p25#0010 will show up in the output of the mmlsrecoverygroup and mmlspdisk commands.

Both the release and replace commands require either a recovery group name and a location code, or a recovery group name and a pdisk name to identify the carrier and particular disk slot within the carrier. It is acceptable to provide more than one location code or pdisk name to replace multiple disks within the same carrier.

The mmchcarrier --resume command reverses the effect of the release command without doing disk replacements. It can be used to cancel the disk replacement procedure after running the mmchcarrier --release command.

Parameters

RecoveryGroupName: Specifies the name of the recovery group to which the carrier belongs. This is used to identify the active server where the low level commands will be issued.
--release: Suspends all disks in the carrier, activates identify lights, and unlocks the carrier.
--resume: Resumes all disks in the carrier without doing disk replacements.
--replace: Formats the replacement disks for use and resumes all disks in the carrier.
--pdisk: Specifies the target pdisk or pdisks and identifies the carrier. All specified pdisks must belong to the same carrier.
--location: Specifies the target pdisk or pdisks and identifies the carrier by location code. All specified pdisks must belong to the same carrier. If this option is used, the location code must be obtained from the output of the mmlspdisk command. There is a field location listed for each pdisk.
--force-release: This is a force flag for the --release option, to release the carrier even if the target is not marked for replacement. This command is intended to temporarily release a carrier. It should not be used to force disk replacement. Disks marked for replacement are identified via the mmlspdisk --replace command.
--force-fru: This is a force flag for the --replace option, to allow the replacement even if the field replaceable unit (FRU) number of the new disk does not match that of the old disk.
--force-rg: This is a force flag for the --release, --resume, and --replace options to allow actions on the carrier even if all the pdisks do not belong to the same recovery group.
--nsd-version: Specifies the desired Nsd version for the replacement disks. The value can be either 1 or 2. This parameter is only effective with recovery group version 4.2.0.1 or up. If the Nsd version for the disks marked for replacement is known, this parameter will be ignored. If the Nsd version for the disk marked for replacement is not known, and if this parameter is not specified, the pdisk Nsd version will be 2 for recovery group version 4.2.0.1 or up. For recovery group version 4.1.0.1 or lower, the Nsd version can only be 1.
-v {yes | no}: Verification flag for the --replace option; indicates whether or not to verify that the new disk does not already have a valid pdisk descriptor. The default is -v yes.
Specify -v no to allow a disk that was formerly part of some other recovery group to be reused.

Exit status

0: Successful completion.
nonzero: A failure has occurred.

Security

You must have root authority to run the mmchcarrier command.

The node on which the command is issued must be able to execute remote shell commands on any other node in the cluster without the use of a password and without producing any extraneous messages. For additional details, see the following IBM Storage Scale RAID: Administration topic: Requirements for administering IBM Storage Scale RAID.

Examples

The following command example shows how to release the carrier containing failed pdisk c014d3 in recovery group 000DE37BOT:

mmchcarrier 000DE37BOT --release --pdisk c014d3

The system displays output similar to the following:

[I] Suspending pdisk c014d1 of RG 000DE37TOP in location 78AD.001.000DE37-C14-D1.
[I] Suspending pdisk c014d2 of RG 000DE37TOP in location 78AD.001.000DE37-C14-D2.
[I] Suspending pdisk c014d3 of RG 000DE37TOP in location 78AD.001.000DE37-C14-D3.
[I] Suspending pdisk c014d4 of RG 000DE37TOP in location 78AD.001.000DE37-C14-D4.
[I] Carrier released.

  - Remove carrier.
  - Replace disk in location 78AD.001.000DE37-C14-D3 with FRU 74Y4936.
  - Reinsert carrier.
  - Issue the following command:

      mmchcarrier 000DE37TOP --replace --pdisk 'c014d3'

The following command example shows how to tell IBM Storage Scale that the carrier containing pdisk c014d3 in recovery group 000DE37BOT has been reinserted and is ready to be brought back online:

mmchcarrier 000DE37BOT --replace --pdisk c014d3