[SOLVED] duplicate/clone an xbian installation

[mk01]

(29th Jul, 2013 10:50 PM)zilexa Wrote:  edit: after reading Fred's post and link I will definitely try rsync. Although creating a backup on the device I want to backup just sounds wrong to me (especially after reading mk01's comment above that post "after one run, run it one more time to copy changes from time during the copy and you are ready.")

the question "why I'm making backup", "for what purpose" must be answered before we choose a strategy.

using snapshots is a excellent way to freeze system / data state at specific point (for example before system upgrade / update). it takes seconds, rollback seconds again. imagine you would sector copy 64GB card each time you run apt-get.

rsync can provide something like incremental backups to extern media, providing backup again media failure - much more efficient as dd. and again, using dd on mounted filesystem can never lead to a atomic and 100% healty copy. it could not on ext2/3/4 and definitely can't on btrfs.

if you are lazy (i'm lazy too), use the shift key "hack" to drop down to initramfs before the rootfs is mounted. that way you can use even dd on btrfs and the copy will work.

or, it's worth try remouting the rootfs as RO, with:

"mount -o remount,ro /"

and do the dd copy as always.

taking into account we are on btrfs, use the native send/recv commands to sends snapshot data from one btrfs/subvolume to another. it's atomic, can be done on RW mounted and used filesystem, will copy only the data (as rsync) and natively supports increments (differences between snapshots). it can be used to local media as well as via network to another system with btrfs support making instant duplicate ready to be used on the other system.