Complete Filesystem Checkpointing?

polymath69 asks: "Living on the edge of Debian unstable means that updates sometimes break stuff, occasionally to an extent that is difficult to recover from. This got me thinking about treating the entire set of mounted filesystems as a transactional database. Mark state, try something which might be dangerous, test, and approve (commit) or panic (rollback). Obviously some filesystem support would be required, but with ext3 and reiserfs available, maybe the potential is already there. And such a system would need lots of disk space, but these days that's a demand easily granted. There's lots out there on process-level checkpointing, and even some stuff about system-level checkpointing, but all I've found on that was in the context of saving and restoring processes for a system freeze and restore. But I couldn't find anything on Google or SourceForge about doing this sort of temporary branching in the filesystem. Is this idea feasible? Is anyone working on it?"

Comments

Backing up

[fava]

What I do is use rsync to backup the company fileserver to a remote machine every 2 hours during business hours. Each update transfers about 10 to 20 MB over DSL/Cable. Then every evening I backup all the files that have changed over the last 24 hours into a seperate dated directory. The first dated backup consisted of the entire server (6 gb) and all the subsiquent backups are about 50 MB a day zipped.

So I have both a snapshot of the current status of the server with 2 hours accuracy and the ability to roll back the server to any point with 24 hours accuracy.

The best part is the company is paying for my Cable connection at home to do this.

Just use Linux LVM

[morzel]

You need to get LVM compiled in your kernel.
LVM provides the ability to create snapshots of your volumes, so you can easily roll back if anything icky happens. Mind you that write perfomance when using the snapshot feature goes down: instead of one write operation, every write becomes a read/write/write operation slowing things down. And this happens for every active snapshot, so you really can't have too much active snapshots :-)

Then again, if it's just for checkpointing (create snapshot), installing experimental stuff and then committing (delete snapshot) or rollback (restore from snapshot, delete snapshot), it should do the trick wonderfully.