[Sheepdog] Sheepdog initial performance

[MORITA Kazutaka]

At Thu, 21 Jul 2011 09:00:20 +0000,
Fernando Frediani (Qube) wrote:
> 
> 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 ?

Yes.  I think Sheepdog shows a good performance on that environment.

> 
> 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.

Each sheepdog image has a metadata to contain the list of allocated
data objects, so it is more similar to QCOW2 than to RAW.  When VMs
write data to the unallocated spaces, there are overheads like QCOW2.

But Sheepdog uses much larger chunk size for the data objects than
QCOW2, so the overhead would be much smaller, I think.

Thanks,

Kazutaka