On Fri, Oct 23, 2015 at 6:55 AM, Julian De Marchi <[email protected] > 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 > [email protected] > http://lists.ovirt.org/mailman/listinfo/users >
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