[Linux-cluster] Storage Problems, need some advice

[David Brieck Jr.]

Some of you may have noticed the problems I've been posting to the
mailing with my storage. For those who haven't here a quick rundown of
my setup:

GNBD Servers w/ clustered SCSI enclosure
GNBD Clients w/ multipath
CLVM
GFS and DLM

I've been having crashes, lockups and poor performance with my setup
almost since it was first setup. I've tried getting rid of multipath
and went down to only one GNBD server but I'm still suffering from
random crashes under moderate to high I/O. I'm not getting any errors
in the logs at all that can help, not even kernel errors any more.

So I've simpled to GNBD Server -> GNBD Clients -> CLVM -> GFS which is
exactly what is specified in the manual:
http://www.redhat.com/docs/manuals/csgfs/browse/rh-gfs-en/ch-gnbd.html
and it still seems to act very flaky. My GNBD Server(s) don't crash,
it's always the client nodes that end up crashing. The only connecting
factor seems to be I/O on the GNBD.

So I have to find a solution that's going to work and I don't think
anything with GNBD is going to work regardless of hardware. So that
pretty much only leaves FC or iSCSI. I don't want to go with FC due to
cost considerations and I already have a GB network setup just for
storage (GNBD) and cluster functions and another for regular LAN
traffic.

So if I go with iSCSI then I can completely get rid of the GNBD aspect
and possibly CLVM as well. However, I am concerned about performance,
especially since I'd want to put MySQL data on it.

The Promise 500i
(http://www.promise.com/product/product_detail_eng.asp?segment=VTrak&product_id=149)
seems like it nice solution (much cheaper than the Dell CX300 I would
also consider) but will it deliver performance wise?

Would you want an enclosure with SCSI drives or SATA drives? And if
you went with SATA drives, would you go with the 10k 1.5Gb drives or
the 7200 3Gb drives for maximum performance?

If you wanted SATA drives is the Promise the best solution? If you
wanted iSCSI with SCSI drives what would you go with?

Thanks for the help, I really need to get this storage situation under control.