Improving disk performance?

Asked by justinsb on 2011-11-02

I'm using OpenStack Diablo with KVM, and disk performance in the guest is not great. Are there any tips for better disk performance?

For example:

Turning on writeback caching is supposed to help (at the expense of reliability)
Switching from ext4 to ext3 is supposed to be a big improvement
Presumably the normal tricks like noatime etc will help
Using a raw disk image rather than a qcow2 disk image could be faster
Switching to a raw LVM partition should be much faster
Mounting "scratch" space (presumably a separate LVM partition again) should be faster than using the root image

Does anyone have any experience with how to get better performance? Any recommended tweaks?

Question information

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Last query:
2011-11-02
Last reply:
2011-11-02
Vish Ishaya (vishvananda) said : #1

Use lxc?

Seriously though, the testing I did long ago had perfectly reasonable disk performance. You could try --nouse_cow_images and see if it helps.

On Nov 2, 2011, at 3:45 PM, justinsb wrote:

> New question #177332 on OpenStack Compute (nova):
> https://answers.launchpad.net/nova/+question/177332
>
> I'm using OpenStack Diablo with KVM, and disk performance in the guest is not great. Are there any tips for better disk performance?
>
> For example:
>
> Turning on writeback caching is supposed to help (at the expense of reliability)
> Switching from ext4 to ext3 is supposed to be a big improvement
> Presumably the normal tricks like noatime etc will help
> Using a raw disk image rather than a qcow2 disk image could be faster
> Switching to a raw LVM partition should be much faster
> Mounting "scratch" space (presumably a separate LVM partition again) should be faster than using the root image
>
> Does anyone have any experience with how to get better performance? Any recommended tweaks?
>
> --
> You received this question notification because you are a member of Nova
> Core, which is an answer contact for OpenStack Compute (nova).

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