Red Hat Bugzilla – Bug 763918
[3.1.1-GA] unknown error 526
Last modified: 2015-09-01 19:05:08 EDT
this is an unrecoverable error you have to restart everything to get things working again.
if bricks part of a volume are down and there has been some "found anamolies in /. holes=1 overlaps=0" messages in logfile, you this error while you mount the volume.
This was fixed as part of the DHT notify() enhancements.