270 reputation
29
bio website ontheroad.net.nz
location Melbourne, Australia
age 32
visits member for 4 years, 3 months
seen Nov 29 '13 at 1:14

Developer, sysadmin and traveller based in Melbourne, Australia.


May
29
awarded  Nice Question
Nov
25
comment Incredibly slow KVM disk performance (qcow2 disk files + virtio)
Nice work. I'm not running the same infrastructure now, so I'm not in a good state to test it, but thanks for the feedback.
Jul
18
comment Incredibly slow KVM disk performance (qcow2 disk files + virtio)
I'm not sure what you mean, sorry; my Update 2 is to do what was suggested in the accepted answer (use raw partitions with LVM).
Feb
12
awarded  Notable Question
Dec
16
awarded  Autobiographer
Oct
31
awarded  Popular Question
Aug
6
comment How to disconnect from lxc-console
"Detach screen: C-a d or C-a C-d" - help.ubuntu.com/community/LXC#Mini_screen_how-to; not sure what to do if that's not working.
Jul
17
comment ubuntu 10.04; kvm bridged networking not working with public ip addresses
Depends on the data center; mine don't allow it either. It's a reasonable decision for them to take and they do provide instructions to work around it, but can't get the damn thing to work anyway... wiki.hetzner.de/index.php/…
Jul
16
awarded  Yearling
Jul
16
revised Incredibly slow KVM disk performance (qcow2 disk files + virtio)
Small tweaks to clarify settings.
Jul
15
comment Incredibly slow KVM disk performance (qcow2 disk files + virtio)
Yeah, I know :) Added new notes anyway, switched to raw on lvm as suggested and performance is where it should be.
Jul
15
revised Incredibly slow KVM disk performance (qcow2 disk files + virtio)
Noted performance improvements when switching to raw on LVM (massive).
Jul
15
accepted Incredibly slow KVM disk performance (qcow2 disk files + virtio)
Jul
15
comment Incredibly slow KVM disk performance (qcow2 disk files + virtio)
I've switched them over to LVM backed raw images on top of RAID1, set the io scheduler to noop on the guest and deadline on the host and it now writes at 138 MB/s. I still don't know what it was that caused the qcow2 to have the 3MB/s speeds, but clearly it can be sidestepped by using raw, so thanks for pushing me in that direction.
Jul
15
comment Incredibly slow KVM disk performance (qcow2 disk files + virtio)
Anyhow, it's a massive digression, I shouldn't have asked. If anyone cares to comment on serverfault.com/questions/91917/… then perhaps that would be a more appropriate place to discuss.
Jul
15
comment Incredibly slow KVM disk performance (qcow2 disk files + virtio)
Oh, Debian has definitely had their problems (three years between stable releases at one time, or thereabouts), so no flame war on that front :) But at least you could use the official backports to get reasonably recent versions on a largely stable system, and they've picked up their game since then. But that is one reason to use Ubuntu over Debian, more packages, more up to date.
Jul
15
revised Incredibly slow KVM disk performance (qcow2 disk files + virtio)
Added a comment on the suddenly improved performance.
Jul
15
comment Incredibly slow KVM disk performance (qcow2 disk files + virtio)
It's probably a whole new question and an invitation to a flame war, I'd be interest to know why you think that. My experience with RHEL and CentOS in the past has been negative, but mainly due to their limited repositories and out of date packages. Having used Debian for more than 10 years, I'd generally been happy with it as a server OS, but I thought I'd play around with Ubuntu this time.
Jul
15
comment Incredibly slow KVM disk performance (qcow2 disk files + virtio)
That's the worst rate on the page, but even if you take that as the example and say that raw is appx. 2.5 times faster than qcow2... multiplying my 3MB/s by 2.5 gets you 7.5MB/s with raw and again, that's not exactly something you'd be happy with.
Jul
15
comment Incredibly slow KVM disk performance (qcow2 disk files + virtio)
The server is in Germany and I'm currently in Mexico, so that could be a little tricky. And if it did suddenly work... I still wouldn't want to have to deal with a Fedora server ;) I have seen a few comments suggesting that Debian/Ubuntu systems did have more issues than Fedora/CentOS for KVM as much of the development work was done there.