NSD and underlying disk subsystem failures

There are indications that will lead you to the conclusion that your file system has disk failures.

Some of those indications include:

Your file system has been forced to unmount. For more information about forced file system unmount, see File system forced unmount.
The mmlsmount command indicates that the file system is not mounted on certain nodes.
Your application is getting EIO errors.
Operating system error logs indicate you have stopped using a disk in a replicated system, but your replication continues to operate.
The mmlsdisk command shows that disks are down.

Note: If you are reinstalling the operating system on one node and erasing all partitions from the system, GPFS descriptors will be removed from any NSD this node can access locally. The results of this action might require recreating the file system and restoring from backup. If you experience this problem, do not unmount the file system on any node that is currently mounting the file system. Contact the IBM® Support Center immediately to see if the problem can be corrected.