On 20/09/2013 15:08, Guy Helmer wrote: > On Sep 19, 2013, at 11:25 AM, Guy Helmer <guy.hel...@gmail.com> wrote: > >> Normally I build VMware ESXi servers with enterprise-class WD SATA drives >> and I/O performance in FreeBSD VMs on the servers is fine. >> Whenever I build a VMware ESXi server with a RAID controller, IO performance >> is awful in FreeBSD VMs. I've previously seen this effect with VMware ESXi >> 3ware 9690SA-8I and 9650 RAID controllers, and now I'm seeing similar >> performance with a Dell 6/iR controller. >> >> Any suggestions would be appreciated. >> >> Guy > > (Replying to self due to hint received off-list) > > I seem to remember controllers mentioned previously by FreeBSD device driver > developers that don't deal well with large I/O requests. It turns out that > may be the case with VMware device drivers as well -- reducing the VMware > Disk.DiskMaxIOSize value from its huge default of 32676KB to 32KB seems to > have helped. Disk ops/sec in the FreeBSD VM are now peaking over 400/sec.
Interesting that the problem shows only on RAID controllers. Do you have any ideas why this reduction helps (did you find a FAQ or a forum post)? The default RAID stripe size in LSI is 64 KiB, maybe it would help even further to align it also?
signature.asc
Description: OpenPGP digital signature
