[Sheepdog] Sheepdog initial performance

[Fernando Frediani (Qube)]

Hi Kazutaka,

Is it ok to use a Raid controller with battery backup and write-cache enabled in order to improve performance and present only one logical drive to sheepdog process ?

In another slightly different topic, when a new image is created on sheedog (e.g: qemu-img create sheepdog:Alice 256G") does do in a similar format of QCOW2 or is it RAW ? Reason I am asking is because I was reading recently about the issue regarding performance for QCOW2. It seems the new driver has got some improvements but still not near of RAW so if that can influence when running on sheepdog.

Thanks

Fernando

-----Original Message-----
From: sheepdog-bounces at lists.wpkg.org [mailto:sheepdog-bounces at lists.wpkg.org] On Behalf Of MORITA Kazutaka
Sent: 21 July 2011 07:43
To: Benjamin Cleyet-Marrel
Cc: sheepdog at lists.wpkg.org
Subject: Re: [Sheepdog] Sheepdog initial performance

At Tue, 19 Jul 2011 11:30:57 +0200,
Benjamin Cleyet-Marrel wrote:
> 
> Hi,
> 
> We are currently in the process of evaluating sheepdog to use as a 
> backend storage for our virtual environement.
> But right now I am facing really  poor performances on unallocated bloc.
> It litterraly takes hours to  convert a 5G file.
> 
> So I am mounting the partition with different option without any luck
> /dev/sdd1 on /var/lib/sheepdog type ext4
> (rw,noatime,user_xattr,barrier=0,data=writeback,nobh)
> Started sheepdog with
> sheep -p 7000 -l 0 /var/lib/sheepdog
> 
> When I issues
> qemu-img convert /images/debian60-64bits.qed -O raw 
> sheepdog:debian60-64bits
> 
> It takes hours to finish altought it is just 5G img.
> The performance from within the virtual machine is then fine. and 
> close to raw performances.
> 
> Is there something I am doing wrong ?

Is the write cache enabled on your disk?  What is the result of 'hdparm -W /dev/sdd'?

Currently, Sheepdog works in a writethrough mode always, but other formats work in a writeback mode when converting images.  So if the write cache is not enabled on your disk, I think it causes a severe difference.


Thanks,

Kazutaka
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