Re: [Qemu-devel] Default cache mode

[Christoph Hellwig]

On Wed, Jun 29, 2011 at 07:23:31AM -0500, Anthony Liguori wrote:
> Which file system on the host?

Any filesystem.  Although extN and btrfs are particularly bad.

> At any rate, I'm a big fan of making wce tunable in the guest and then I 
> think setting wce=1 is quite reasonable to do by default.

Note that this means a manual override during each boot.  Windows and
modern Linux just use what's available.  Only Solaris with ZFS actually
turns WCE on if it's not set AFAIK.  And to me it's a rather questionable
behaviour at least for SCSI disks where the admin might have chosen
those intentionally.  (unlike ATA disks SCSI allows to store the setting
permanently)