A recent change in the UEFI driver update for the SAS HBA can result in damage to any disks used for GPFS which previously contained a GPT partition table (due to non-GPFS use) but are now assigned to GPFS, on upgrade.
The UEFI firmware includes a function for Disk GPT Table Recovery. This function will restore the GPT table from the backup GPT table which was stored at the end of the disk, and it is the default function. When a disk contains a backup GPT table but is later used as a GPFS NSD, the GPT Table Recovery action could rewrite GPFS NSD and Disk descriptor headers with the backup GPT table. Thus such NSDs will be lost after the GPT Table Recovery action.
This problem may affect Linux customers who have GPFS NSDs that were created with GPFS version 3.5 or earlier, and these disks were partitioned before they were used for a GPFS NSD.
An nsdcheck script is available to run against NSD devices to determine if there is a valid backup GPT table on the device. An NSD disk is at risk if the remarks display hasPrimaryGpt=no,hasSecondaryGpt=yes. If the backup table is not valid, the script can then be used to clear the backup GPT table on the NSD device, prior to any firmware updates, as soon as is possible.
Running this script is recommended for all Linux customers, as a precaution. The script when used to remove the secondary GPT will only remove it IF AND ONLY IF there is a GPT signature on the last sector of the NSD device but not at the beginning .
The script is available:
1. In the samples directory with GPFS V220.127.116.11 and V18.104.22.168 from FixCentral
2. As an attachment to this post.
Note: If you need to restore the secondary GPT signature from GptBackupFile to disk, contact IBM Service. This should not be done without guidance.