[Users] Pstorage and read-only FS problem

Corrado Fiore lists at corradofiore.it
Sat Jan 16 01:26:39 PST 2016


Dear All,

we had recently experienced a filesystem corruption issue on a big-ish host where the HW RAID card suddenly started to behave erratically.

After a few minutes, the OS (OVZ kernel 2.6.32) put the /vz filesystem in read-only, which forced us to shut down the entire node, check the FS with the usual tools, etc. and ultimately lead to a significant downtime.

On that node we weren’t using pstorage - just a regular EXT4 file system on top of the RAID array… which brings us to my question for the pstorage experts on the list.

Let’s assume that instead of a regular EXT4 file system, we were using pstorage with 5 or more nodes and triple redundancy.

In a case where the entire FS of a pstorage chunk server suddenly becomes read-only, but the server itself is still on and responding to network probes, does the pstorage fencing mechanism automatically intervene to exclude that chunk server?

In simple terms, I am trying to find out whether in such a case pstorage (coupled with HA features of the commercial Virtuozzo) would have prevented downtime.  I suspect it would, just searching for some official confirmation from the experts.  :-)

Thanks a lot,
Corrado Fiore


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