On 02/25/2017 06:30 PM, Wols Lists wrote: > On 25/02/17 22:00, Phil Turmel wrote: >> No. Don't go there. There's already a technology out there that does >> this correctly, called LVM snapshots. And they let you resume normal >> operations after a very brief hesitation, and the snapshot holds the >> static image while you copy it off. > > Will it let you put that snapshot on a hot-plug disk you can remove? For > my little system I'd quite happily mirror it off onto a hard-disk and > unplug it. You can copy it off to any block device you like, or dd it to a file, or dd and gzip to a compressed file. Anything you can do to copy a partition to backup can be used on the snapshot. > Oh - and I'm not running lvm. Not that I think there's anything wrong > with that, it's just yet another layer that I'm not (currently) > comfortable with. So you know how to use a hammer, and don't feel comfortable with using a handsaw, so you're going to smash a board in two instead of sawing it? Ok, maybe that was too facetious. (-: > Is there a sound technical reason not to go there, or is it simply a > case of "learn another tool for that job"? The less tools I have to know > the better, imho. Um, no, imnsho. Learn new tools when you need them. Linux raid has no formal mechanism to cleanly separate a mirror from a running array, access it as a backup, and not risk corruption when re-attaching it to the array. Most filesystems write to the partition when mounting, even for read-only mounts. You cannot safely access the disconnected member except via pure block reads. Phil -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
