I have some question about a performance problems:
we set up a vmware server on top of a SuSE 10.1 system
with two opteron CPUs and 8GB of memory. Running vmware
server, we currently run about 16 guest VMs, mainly running
different kinds of Windows systems. Most of them are more
ore less idle. Frequently, however, the system starts
thrashing with 20-50% iowait, and users of the different
vmware clients complain about "system unusable". If this
continues, I have to stop my VMware experiments, before
people are killing me...
The problem is: i can't find who causes this excessive
iowait. I see 4 cpus almost idle, there is about 6GB
memory available. "top" shows a few vmware-vx processes
at 5-8% CPU. Using "iostat" i see a high IO rate on the
partition containing my VMware images, but I can't assign
this IO to any process.
All vmware images reside on an ext3 system on an 3ware raid
controller with 6x500GB SATA disks. "hdparm -t" reaches about
270 Mb/s, so this is not really "slow".
Any idea how to find the bottleneck?
Dieter.