[Linux-cluster] sudden slow down of gfs2 volume

[Dil Lee]

Hi,

I have a centos 6.5 cluster that are connected to a Fibre Channel SAN in star
topology. All nodes/SAN_storages have single-pair fibre connection and
no multipathing. Possibility of hardware issue had been eliminated
because read/write between all other node/SAN_storage pairs works
perfectly.

Problem:
Everything was running perfectly for years. Then node3 suddenly has
very slow write to SAN_storage1, ~10KB/sec. Read speed seems to remain
normal.

Can anyone give be some pointers to debug the problem. Thank you.

Dil