HP Serviceguard Extended Distance Cluster for Linux A.11.20.10 Deployment Guide, December 2012

7 Troubleshooting
This chapter describes how to troubleshoot issues related to serviceguard-xdc package.
7.1 Troubleshooting serviceguard-xdc packages
Symptom:
/dev/hpdev/mylink-sde cannot be added to /dev/md0 which means /dev/md0 is running
with only one mirror half. The following message is logged into the package log file:
mdadm: /dev/hpdev/mylink-sde reports being an active member for /dev/md0, but a --re-add fails.
mdadm: not performing --add as that would convert /dev/hpdev/mylink-sde in to a spare.
mdadm: To make this a spare, use "mdadm --zero-superblock /dev/hpdev/mylink-sde" first.
Problem Description:
When a package (P1) is running on a node (Node 1). The package uses a mirror (md0) that
consists of two corresponding mirror half. S1 (local to /dev/hpdev/mylink-sde) and S2
(/dev/hpdev/mylink-sdf local to Node 2). Access to S1 is lost from both nodes, either due
to the power failure to S1 or loss of FC links to S1. Once you restore the power to S1, or restore
the FC links to S1, the corresponding mirror half of S1 (/dev/hpdev/mylink-sde) is accessible
from Node 1.
NOTE: The log message is seen only on SUSE Linux Enterprise Server 11 SP2.
Workaround:
1. Ensure that the link to /dev/hpdev/mylink-sde exists:
#ll /dev/hpdev/mylink-sde
2. If the link to /dev/hpdev/mylink-sde does not exist, run the following command:
#udevadm trigger
3. Confirm that the link to /dev/hpdev/mylink-sde exists:
#ll /dev/hpdev/mylink-sde
lrwxrwxrwx 1 root root 3 Aug 10 11:36 /dev/hpdev/mylink-sde ->../sde
If you still see the log message being logged after rectifying the udev links, there is an issue with
mdadm --add command. To resolve the mdadm --add issue, complete the following steps:
1. Halt the package:
#cmhaltpkg pkg1
2. Run the following commands:
mdadm --zero-superblock /dev/hpdev/mylink-sde
mdadm --add /dev/md0 /dev/hpdev/mylink-sde
3. Stop the MD device:
#mdadm -S /dev/md0
4. Start the MD device outside of the package.
#mdadm -A -R /dev/md0 /dev/hpdev/mylink-sde /dev/hpdev/mylink-sdf
5. Verify if the MD device is started with two devices:
#cat /proc/mdstat
Personalities : [raid1]
md0 : active raid1 sde[0] sdf[1]
7.1 Troubleshooting serviceguard-xdc packages 41