On 11/13/2015 01:46 AM, J Martin Rushton wrote: > If you really_need_ the guarantee of a snapshot, consider either LVM > or RAID1. Break out a volume from the RAID set, back it up, then > rebuild. FFS, don't do the latter. LVM is the standard filesystem backing for Red Hat and CentOS systems, and fully supports consistent snapshots without doing half-ass shit like breaking a RAID volume. Breaking a RAID volume doesn't make filesystems consistent, so when you try to mount it, you might have a corrupt filesystem, or corrupt data. Breaking the RAID will duplicate UUIDs of filesystems and the name of volume groups. There are a whole bunch of configurations where it just won't work. At best, it's unreliable. Never do this. Don't advise other people to do it. Use LVM snapshots (or ZFS if that's an option for you).