@Phillip Susi / comment #23: Did you actually read what I wrote? :) I was *NOT* advocating "backup" by having multiple RAID disks constantly connected to the array and in sync. It is completely obvious to me that a hot running copy of data is NOT a backup. I was advocating the following procedure: 1. Connect disk 2. Wait until it is synced into the array. 3. Shutdown the machine 4. *DISCONNECT* the disc from the machine and consider the completely offline disk as a backup.
This is a backup because the disk is physically disconnected from the machine. It is much better than a rsync/cp, because it provides a *coherent* copy since all modifications to the data which happen during the copying process are also applied on the backup. With rsync/cp, files which are modified *after* they have already been copied are not up to date in the backup, and for applications which store data in multiple files (which *many* programs do), their data would be corrupt in such a case. It is relevant to this bugtracker entry because it shows that using multiple kinds of disks in a RAID1, such as SATA+USB, is a common desire and not some exotic border case. Or can you name any other kind of non-exotic, non-beta (such as btrfs) backup mechanism which can copy data while the system is in use without breaking its coherency? :) -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/320638 Title: hot-add/remove in mixed (IDE/SATA/USB/SD-card/...) RAIDs with device mapper on top => data corruption (bio too big device md0 (248 > 240)) To manage notifications about this bug go to: https://bugs.launchpad.net/linux/+bug/320638/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
