On Wed, Jul 03, 2013 at 12:24:24PM +0200, Nicolas Sebrecht wrote: > The 03/07/13, Jamie Fargen wrote: > > > Hey! > > > > I have some RHEL6 hypervisors and the VMs are in raw qemu image files in a > > local raid array linux raid + lvm + ext3. When a kernel update is installed > > a reboot is necessary, usually it has been more than 180 days since the > > last reboot and the file system is fsck'd and this takes 2-3 hours. > > > > I am curious to know if there is any documentation that addresses the pro's > > and con's of fsck'ing the volume containing /var/lib/libvirt/images. > > This is standard ext fsck to prevent errors after some time. > > In order to avoid long fsck times, we use ext4 almost everywhere (for > both hypervisors and guests). I would suggest you to switch to a newer > filesystem supporting fast fsck. > > > Could fsck make a change to the underlying file system that the guest > > images are stored on, which the guest operating system may not be able to > > handle when it runs its own file system maintenance, i.e. fsck or chkdsk. > > Talking about filesystems errors, you should assume that everything is > possible. Though, the fsck on /var/lib/libvirt/images is limited to the > filesystem used by the hypervisor and should not interfere with the > filesystems of the guests. An exception I'm aware of is a reiserfs > filesystem inside another reiserfs filesystem (/var/lib/libvirt/images > is reiserfs and the guests are in reiserfs, too). > > > Is file system maintenance on the hypervisor volume storing the VM images > > redundant to the VM's own file system consistancy utilities. > > As said above, it's not redondant. The fsck at hypervisor level keeps > limited to the filesystem at hypervisor level. Of course if you think that having 2 fscks is overkill, then you could also change the way you storage images on the host. eg, use an LVM volume for each guest disk, instead of storing them in /var/lib/libvirt/images. That way the guest OS is 100% responsible for its data integrity and you don't waste I/O bandwidth by having duplicate fscks in host & guest. Daniel -- |: http://berrange.com -o- http://www.flickr.com/photos/dberrange/ :| |: http://libvirt.org -o- http://virt-manager.org :| |: http://autobuild.org -o- http://search.cpan.org/~danberr/ :| |: http://entangle-photo.org -o- http://live.gnome.org/gtk-vnc :| _______________________________________________ libvirt-users mailing list libvirt-users@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/libvirt-users
