Topics: AIX, SSA, Storage

SSA batteries

To find the status of the batteries of an SSA adapter, enter as root:

# ssa_fw_status -a ssaX
X is the number of your adapter, for example:
# ssa_fw_status -a ssa0
Fast write cache size: 32
Expected battery life: 22000
Powered on hours: 20706
Battery state: Active
After installing a new battery, enter the following command:
# ssa_format - l ssaX - b
This will reset the lifetime counter.

Topics: AIX, SSA, Storage, System Administration

Renaming pdisks

If, for some reason, the pdisk and hdisk numbering of SSA disks is not sequential anymore, then there's a way to bring order in to chaos. Usually, the pdisk and hdisk numbering order are screwed up when you replace multiple disks together. Especially on HACMP clusters, a correct numbering of pdisks and hdisks on all nodes of the cluster, comes in handy.

Unmount all file systems on the specific disks, then varyoff the volume group:

# /usr/lib/methods/cfgssar -l ssar
If this doesn't help (it sometimes will), then renumber the disks manually:

Write down the pdisk names, hdisk names, location of the disks in the SSA drawer and the connection ID's of the disks. You can use lsdev -Cc pdisk to show you all the pdisks and the drawer and location codes. Use lsdev -Clpdiskx -Fconnwhere to show the connection ID of a pdisk. Then, figure out, how you want all disks numbered.

Remove the pdisks and hdisks with the rmdev -dl command.
Create the pdisks again:
# mkdev -p ssar -t scsd -c pdisk -s ssar -w [connection-ID] -l pdisk1
Create the hdisks again:
# mkdev -p ssar -t hdisk -c disk -s ssar -w [connection-ID] -l hdisk3
Test with:
# ssaxlate -l pdisk1
if it shows hdisk3 (Usually the hdisk number is 2 higher than the pdisk number if you use 2 SCSI disks in the rootvg).

If you've done all disks this way, check with lsdev -Cc pdisk. If you're happy, then varyon the volume group again and mount all filesystems.

Topics: AIX, SSA, Storage

SSA Fast Write

For high-disk performance systems, such as SSA, it is wise to enable the fast write on the disks. To check which disks are fast write enabled, type:

# smitty ssafastw
Fast write needs cache memory on the SSA adapter. Check your amount of cache memory on the SSA adapter:
# lscfg -vl ssax
Where 'x' is the number of your SSA adapter. 128MB of SDRAM will suffice. Having 128MB of SDRAM memory makes sure you can use the full 32MB of cache memory.

To enable the fast write the disk must not be in use. So either the volume groups are varied offline, or the disk is taken out of the volume group. Use the following command to enable the fast write cache:
# smitty chgssardsk

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