OpenStack Compute (nova)

Improving disk performance?

Asked by justinsb

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?

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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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