On Mon, 13 Nov 2017 22:39:44 -0500 Dave <davestechs...@gmail.com> wrote:
> I have my live system on one block device and a backup snapshot of it > on another block device. I am keeping them in sync with hourly rsync > transfers. > > Here's how this system works in a little more detail: > > 1. I establish the baseline by sending a full snapshot to the backup > block device using btrfs send-receive. > 2. Next, on the backup device I immediately create a rw copy of that > baseline snapshot. > 3. I delete the source snapshot to keep the live filesystem free of > all snapshots (so it can be optimally defragmented, etc.) > 4. hourly, I take a snapshot of the live system, rsync all changes to > the backup block device, and then delete the source snapshot. This > hourly process takes less than a minute currently. (My test system has > only moderate usage.) > 5. hourly, following the above step, I use snapper to take a snapshot > of the backup subvolume to create/preserve a history of changes. For > example, I can find the version of a file 30 hours prior. Sounds a bit complex, I still don't get why you need all these snapshot creations and deletions, and even still using btrfs send-receive. Here is my scheme: ============================================================================ /mnt/dst <- mounted backup storage volume /mnt/dst/backup <- a subvolume /mnt/dst/backup/host1/ <- rsync destination for host1, regular directory /mnt/dst/backup/host2/ <- rsync destination for host2, regular directory /mnt/dst/backup/host3/ <- rsync destination for host3, regular directory etc. /mnt/dst/backup/host1/bin/ /mnt/dst/backup/host1/etc/ /mnt/dst/backup/host1/home/ ... Self explanatory. All regular directories, not subvolumes. Snapshots: /mnt/dst/snaps/backup <- a regular directory /mnt/dst/snaps/backup/2017-11-14T12:00/ <- snapshot 1 of /mnt/dst/backup /mnt/dst/snaps/backup/2017-11-14T13:00/ <- snapshot 2 of /mnt/dst/backup /mnt/dst/snaps/backup/2017-11-14T14:00/ <- snapshot 3 of /mnt/dst/backup Accessing historic data: /mnt/dst/snaps/backup/2017-11-14T12:00/host1/bin/bash ... /bin/bash for host1 as of 2017-11-14 12:00 (time on the backup system). ============================================================================ No need for btrfs send-receive, only plain rsync is used, directly from hostX:/ to /mnt/dst/backup/host1/; No need to create or delete snapshots during the actual backup process; A single common timeline is kept for all hosts to be backed up, snapshot count not multiplied by the number of hosts (in my case the backup location is multi-purpose, so I somewhat care about total number of snapshots there as well); Also, all of this works even with source hosts which do not use Btrfs. -- With respect, Roman -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
