It looks like this time I finally caught the long standing SSI-1.9 CFS
soft mount bug that hangs the cluster on very large file transfers.
Dirty pages accumulate on the cmi sb and don't get writeback until
memory starvation which hangs ICS until sys_sync() at CFS server. At
first I thought this was an ICS throttling problem. Maybe we just
didn't notice the difference between base kernel 2.4 and 2.6