Actually you create a doubt in my mind... If you have a VM with lots of memory, if you just suspend the machine, and back it up without saving the ram, in teory, as no fsync succeded you could lose a lot of stuff which is in the filesystem cache and not synced. Am I wrong ?
Regards Chris On Tue, 2011-04-12 at 17:50 +0200, Frédéric Grelot wrote: > > Actually, this isn't right. Think about the case where you lose > > power to > > your computer; you don't get corrupted disks, you get > > "crash-consistent" disks > > (this is what journaling filesystems are for). So if you know what > > you are > > doing, it is sufficient just to pause the guest (virsh suspend > > <guest>), take > > the backup, and then resume the guest (virsh resume <guest>). True, > > you > > won't get all of the data that might have been in-flight in memory, > > but it > > should be a valid state of the disk. > > I tend to agree with that, it already happened to me for a zimbra server, and > I lost nothing. > > > > > That all being said, installing backup software in the guest is the > > best > > course of action. > > An other method to profit from virtualization-enabled server would be to take > the following actions : > -inside guest : turn of server application > -inside guest : unmount data disk > -host : pause guest (necessary?) > -host : lvm (or qcow/qed) snapshot of disk > -host : resume guest > -inside guest : remount and restart server application > > Provided there is no side-effect of unmounting with regard to guest cache (to > be confirmed), I think this would reduce downtime, and permits backup of > specific parts of the server application without stopping it as a whole. > A (maybe safest) other option would be to gracefully shutdown the server, > LVM/qcow/qed snapshot its disk and restart the server immediately : the data > duplication itself won't account for the downtime, since it can be done later. > > Frederic. > > > > > -- > > Chris Lalancette > > > > _______________________________________________ > > virt-tools-list mailing list > > [email protected] > > https://www.redhat.com/mailman/listinfo/virt-tools-list > > > > _______________________________________________ > virt-tools-list mailing list > [email protected] > https://www.redhat.com/mailman/listinfo/virt-tools-list _______________________________________________ virt-tools-list mailing list [email protected] https://www.redhat.com/mailman/listinfo/virt-tools-list
