[libvirt] cache=none
Hello, * Is it possible to add the "kvm -drive"-option "cache=none" to libvirtd.conf ? It's a recommendation of XFS FAQ: http://xfs.org/index.php/XFS_FAQ#Q:_Which_settings_are_best_with_virtualizat... * Is there a generic way to handle kvm options that are not supported in libvirtd.conf ? * Is it generally a bad idea to use XFS with KVM ? Thanks Stefan
On Thu, Oct 22, 2009 at 05:23:55PM +0200, Stefan wrote:
Hello,
* Is it possible to add the "kvm -drive"-option "cache=none" to libvirtd.conf ? It's a recommendation of XFS FAQ: http://xfs.org/index.php/XFS_FAQ#Q:_Which_settings_are_best_with_virtualizat...
Add this within the <disk> element <driver cache='none'/>
* Is there a generic way to handle kvm options that are not supported in libvirtd.conf ?
Submit an RFE for the option in question :-)
* Is it generally a bad idea to use XFS with KVM ?
I don't know of any problems with using XFS, there was a bug a long while back with a combo of AIO + sparse files, but that's long since fixed. Daniel -- |: Red Hat, Engineering, London -o- http://people.redhat.com/berrange/ :| |: http://libvirt.org -o- http://virt-manager.org -o- http://ovirt.org :| |: http://autobuild.org -o- http://search.cpan.org/~danberr/ :| |: GnuPG: 7D3B9505 -o- F3C9 553F A1DA 4AC2 5648 23C1 B3DF F742 7D3B 9505 :|
* Is it generally a bad idea to use XFS with KVM ?
I don't know of any problems with using XFS, there was a bug a long while back with a combo of AIO + sparse files, but that's long since fixed.
There are several warnings using XFS with KVM because of the intensive Write-Caching. Are these warnings obsolete ? cache=none in libvirtd.conf is not necessary anymore (sorry I'm a kvm/libvir-beginner) ? Stefan
On Thu, Oct 22, 2009 at 06:33:25PM +0200, Stefan wrote:
* Is it generally a bad idea to use XFS with KVM ?
I don't know of any problems with using XFS, there was a bug a long while back with a combo of AIO + sparse files, but that's long since fixed.
There are several warnings using XFS with KVM because of the intensive Write-Caching. Are these warnings obsolete ? cache=none in libvirtd.conf is not necessary anymore (sorry I'm a kvm/libvir-beginner) ?
Enabling write caching is dangerous on any filesystem in the event of the host OS crashing before data is flushed. I don't think XFS is special in this regard really. Everyone should disable write caching unless they don't care about their data. Daniel -- |: Red Hat, Engineering, London -o- http://people.redhat.com/berrange/ :| |: http://libvirt.org -o- http://virt-manager.org -o- http://ovirt.org :| |: http://autobuild.org -o- http://search.cpan.org/~danberr/ :| |: GnuPG: 7D3B9505 -o- F3C9 553F A1DA 4AC2 5648 23C1 B3DF F742 7D3B 9505 :|
participants (2)
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Daniel P. Berrange -
Stefan