Hello,
The cache settings would also depend on the underlying storage. If you are planning to use something like ext4 partition on the local harddisk then cache=none would be suitable.

It would be good to avoid cache=writeback on production environment as there no guarantees that the write actually got saved to harddisk.

cache=writethrough though slower than writeback is the most recommended for the production environments.

To get better performance it would be good to identify what additional performance can be extracted from the underlying storage subsystem.

Thanks and Regards
Saurav Lahiri
Hexagrid Computing

--- On Sun, 5/2/12, Stefan G. Weichinger <lists@xunil.at> wrote:

From: Stefan G. Weichinger <lists@xunil.at>
Subject: [libvirt-users] qcow2 performance
To: libvirt-users@redhat.com
Date: Sunday, 5 February, 2012, 18:31

Greets,

I have to research performance-issues of a W2003-VM within KVM.

Right now it's a qcow2-image-file w/ default settings within libvirt
(configured by vmm ...)

My question:

what caching to use?

writeback/writethrough/etc ... what to use for data integrity while not
getting ultraslow performance?

Found

https://www.linuxfoundation.jp/jp_uploads/JLS2009/jls09_hellwig.pdf

Is there any other list/doc what to use and why?

Thanks, Stefan

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