On 02/25/2017 03:05 PM, Anthony Youngman wrote: > Although I would have thought build mode was superb for doing > backups without needing to stop using the system ... I haven't seen > any documentation about things like breaking raid to do backups and > all that sort of thing. > > I need to investigate it, but I'd like to know how to suspend a > mirror, back it up, and then resume. The databases I work with have > an option that suspends all new writes, but flushes all current > transactions to disk so the disk is consistent for backing up. So if > you do that and back up the database you know your backup is > consistent. > > This is all a rather important usage of raid, actually, imho. It > seems so obvious - create a temporary mirror, wait for the sync to > complete, suspend i/o to get the disk consistent, then you can break > the mirror and carry on. Terabytes :-) of data safely backed up in > the space of seconds. 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. 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
