<div dir="ltr"><div class="gmail_extra"><div class="gmail_quote">On Fri, Oct 23, 2015 at 6:55 AM, Julian De Marchi <span dir="ltr"><<a href="mailto:julian@jdcomputers.com.au" target="_blank">julian@jdcomputers.com.au</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">heya--<br>
<br>
Playing around with oVirt 3.6 on some new kit before I rack and stack in the DC.<br>
<br>
- Dell Eql PS4210(Raid-6)<br>
- Dell R630<br>
- Dell N400 10GB switch<br>
<br>
I have my 10GB interfaces bonded and in a port-channel. I have setup a basic 3.6 oVirt self-hosted stack.<br>
<br>
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.<br>
<br>
On the engine I'm seeing this:<br>
<br>
# dd if=/dev/zero of=~/testfile bs=1G count=1 oflag=dsync<br></blockquote><div><br></div><div>You are not using direct IO, please add relevant flag.</div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
1+0 records in<br>
1+0 records out<br>
1073741824 bytes (1.1 GB) copied, 1.58877 s, 676 MB/s<br>
<br>
On a test VM I'm seeing this:<br>
<br>
# dd if=/dev/zero of=~/testfile bs=1G count=1 oflag=dsync<br>
1+0 records in<br>
1+0 records out<br>
1073741824 bytes (1.1 GB) copied, 22.0732 s, 48.6 MB/s<br>
<br>
I have played with the disk drivers for my guest VM, changing between drivers does not change the speed at all.<br></blockquote><div><br></div><div>I assume both VMs have the same image format and drivers?</div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<br>
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.<br>
<br>
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.<br></blockquote><div><br></div><div>dd is by no means a tool for disk speeds. Specially not when you are writing zero's. I suggest fio .</div><div>Y.</div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<br>
Many thanks!<br>
<br>
--julian<br>
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</blockquote></div><br></div></div>