[Linux-cluster] GFS lockups ?

[Janar Kartau]

Hi,
Recently our three-node webserver cluster started randomly crashing. I
never had time to investigate what the problem was, cause i needed to
bring them back online again. But it seemed like alla Apache processes
just hang (couldn't even kill them).. waiting for something. The only
thing that helped, was a reboot for all or couple of the nodes. Anyway,
today i encountered this problem at night and i could look into it a
little more. I noticed that some of the GFS filesystems were
unaccessable (we have 5 of them, mounted on every nide) and of the nodes
was completely unaccessable. So i guessed that this half-dead node was
holding locks on the filesystems or sth. Did a hard reset on this dead
node and all stabilized.
Absolutely no cluster/GFS errors in the logs (besides the ones which
tell that the half-dead node was leaving the cluster when i reset it).
Nodes have CentOS 4.6 installed (2.6.9-67.0.7.ELsmp, dlm-1.0.7-1,
GFS-6.1.15-1, cman-1.0.17-0.el4_6.5). We use EMC CX3-10c for GFS storage
(over iSCSI) and EMC PowerPath for multipathing. Separate VLAN is used
for CMAN/DLM traffic.
Please give me ideas how to solve this or atleast some debugging tips as
it's happening twice a day now and seems i simply can't help it. :(

Janar Kartau