[SAGE] Which heuristics do you use with a quorum disk on RHAS4?

[Marco Marongiu <brontolinux@gmail.com>]

Hello there

We are using the Red Hat Cluster Suite on an Red Hat Linux Advanced
Server 4 in order to support a small number of shared GFS filesystems.

We found we needed a quorum disk in order to make the cluster more
reliable, and we are working on it.

I don't have a large experience in cluster environments, and it is
limited to SunCluster, where the management of the quorum device is, in
some sense, completely in the hands of the cluster itself and you don't
have to establish heuristics on your own. This makes me a bit
disoriented for what I found on the qdisk(5) manpage:

> 2.2. Scoring & Heuristics
>        The  administrator can configure up to 10 purely arbitrary
> heuristics,
>        and must exercise caution in doing so.  At  least  one 
> administrator-
>        defined  heuristic  is  required  for operation, but it is
> generally a
>        good idea to have more than one heuristic.
>
> [...]
>
>        The  heuristics  themselves  can be any command executable by
> ’sh -c’.
>
> [...]
>
>        Typically, the heuristics should be snippets of shell code or
> commands
>        which  help  determine  a node’s usefulness to the cluster or
> clients.
>        Ideally, you want to add traces for all of your  network 
> paths  (e.g.
>        check  links,  or ping routers), and methods to detect
> availability of
>        shared storage.
>
For those who already use RHCS: what kind of heuristics do you use?
For everybody: what kind of heuristics would you advise as sensible?

Thanks for your help

Ciao
--bronto