On Fri, Oct 23, 2015 at 6:55 AM, Julian De Marchi <julian@jdcomputers.com.au
wrote:
heya--
Playing around with oVirt 3.6 on some new kit before I rack and stack in the DC.
- Dell Eql PS4210(Raid-6) - Dell R630 - Dell N400 10GB switch
I have my 10GB interfaces bonded and in a port-channel. I have setup a basic 3.6 oVirt self-hosted stack.
I am seeing some pretty big differences in disks speeds from the self-hosted engine and a VM guest. Both are direct luns via iscsi from the SAN on the 10GB port-channel. Normal network traffic does not go over the 10GB.
On the engine I'm seeing this:
# dd if=/dev/zero of=~/testfile bs=1G count=1 oflag=dsync
You are not using direct IO, please add relevant flag.
1+0 records in 1+0 records out 1073741824 bytes (1.1 GB) copied, 1.58877 s, 676 MB/s
On a test VM I'm seeing this:
# dd if=/dev/zero of=~/testfile bs=1G count=1 oflag=dsync 1+0 records in 1+0 records out 1073741824 bytes (1.1 GB) copied, 22.0732 s, 48.6 MB/s
I have played with the disk drivers for my guest VM, changing between drivers does not change the speed at all.
I assume both VMs have the same image format and drivers?
What ideas do you folks have for me to narrow down this slow down? I don't really know where to start with this one. I also noticed that 3.6 does not yet have ovirt-guest-agent available.
I know DD is not the best test for disk speeds, but it works for what I need right now, iozone will be next when I'm happy.
dd is by no means a tool for disk speeds. Specially not when you are writing zero's. I suggest fio . Y.
Many thanks!
--julian _______________________________________________ Users mailing list Users@ovirt.org http://lists.ovirt.org/mailman/listinfo/users