On Tue, Oct 07, 2008 at 10:26:47AM +0200, Paul Bijnens wrote: > On 2008-10-06 10:39, Pasi Kärkkäinen wrote: > >On Sun, Oct 05, 2008 at 11:28:45AM +0200, Paul Bijnens wrote: > >>We are struggling with a strange problem. > >>When we have some VMWare clients running (mostly MS windows clients), > >>than the IO-write performance on the host becomes very bad. > >>The guest os's do not do anything, just having them started, > >>sitting at the login prompt, is enough to trigger the problem. > >> > >>The host has plenty of 4G of RAM, and all clients fit easily into > >>the space. > >>The disksystem is a RAID5 (ok, not the fastest choice). > >> > >>Both hosts are running the latest CentOS 5.2 (but the problem was > >>already present in 5.0 as well), and running the latest production > >>version of VMWare server 1.0.7 (but when running 1.0.5 the problem > >>was there too). > >> > > > >Hello. > > > >I assume you know VMware server v1.x is not supported on RHEL5/CentOS5.. > > > >Have you tried VMware server v2.0? > > You wouldn't believe now many times i've checked to see if 2.0 was > in production. I did not verify before sending this mail. > > Also, because it was rather difficult to test beta software on these > servers (only limited time in the weekends were free to test variations > in the setup), I did not try to run 2.0beta. > > To my surprise indeed 2.0 is now out of beta indeed. I installed it, > and indeed, it works! No performance loss, even with 4 VM guests > running. > > Case closed. > Nice. > > >20 MB/sec sounds really bad. There has to be something wrong with your > >raid/disk setup. > > I don't believe 20MB/s sustained write performance is too bad for RAID5 > with 4 sata disks, in a inexpensive machine. Do you do much better? > Not me, but: http://home.comcast.net/~jpiszcz/20080607/raid5-benchmarks-3to10-veliciraptors/veliciraptor-raid.html 4 disk raid5: sequential writes: 297 MB/sec sequential reads: 407 MB/sec I remember seeing >100 MB/sec sequential reads and writes with at least 4 years old hardware and 4x sata-disk (7200 rpm) software md-raid5. -- Pasi