[Linux-cluster] best qdisk location

Jan Huijsmans Jan.Huijsmans at interaccess.nl
Wed Jan 25 12:07:05 UTC 2012


When checking the RedHat cluster set-up I was surprised to find the quorum disk located
on the same LUN as the database. This location was chosen because the database LUN
needs to be accessable for the node to be able to service the environment.
It's a logical choice.

However, at this moment we're experiencing latency on the storage, which also hinders
the usage of the qdisk. There are lots of time-outs on disk activity which won't hinder the
application much, at least when the cluster won't reboot due to time-outs on the qdisk.

For me the logical choice for the qdisk would be a seperate LUN on a fast disk, we have
a quorum disk library for the SAN with unused disks, instead on the same LUN that's
being used by the application. (in a cabinet that's used by the complete environment.

This way the qdisk can be fast and it's a real quorum LUN, as it's located on the quorum
location of the SAN controllers.

My main question is which method would give the most stable environment for the cluster.

1. qdisk on same LUN as application
2. qdisk on seperate, isolated, LUN

I would choose the second option, but I'm not sure which would give the stability I'm seeking.


Jan Huijsmans

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