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timeshift with btrfs: am I doing it right?
(lemmy.kde.social)
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this post was submitted on 20 Jul 2023
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Yep, you're doing it right... or at least that's how I do it as well, lol 😂.
A snapshot is exactly that, a snapshot. It doesn't take forever to create, like with rsync, it litelarly takes a second, even on very old rigs (775 or even older). It's basically a snapshot of what the current drive holds. If a file changes (gets added, removed, whatever), the snapshot grows cuz it needs to hold the older versions of the files (the ones saved at the time of the snapshot).
This might not be exactly how snapshots work in BTRFS, but this is what I gathered from using it with snapshots enabled. The older the snapshot, the larger the size of the snapshot (takes way more room cuz more changes have occured).
Also, it's wise to set up daily, weekly and monthly snapshots. I have it set up to hold 5 or 6 (can't really remember now) daily snapshots, 4 weekly and 2 montly. So basically, I can go back in time for a max of 2 months. I was thinking or raising the montly snapshots to 3 or 4, but I'm still not sure. Still, I wouldn't go lower than 2.
wouldn't this take a lot of disk space?
Depends on how much you change per time unit.
I take full system backups every three hours, but the backups are thinned so that there are previous 24 hourly ones, previous n daily ones, previous m monthly ones, etc. Similar approach can be used with snapshots.
I don't currently use snapshots—I don't run btrfs anymore—but when I did, I did a snapshot every hour and kept them for 24 hours. But then I backed up the latest snapshot, which gives consistent backups, versus regular backups where files can change while you're doing them. I'm nowadays using bcachefs, but I don't quite trust its snapshots yet so I haven't started using them ;).
Haven't heard of this FS, so I checked the specs... was actually hoping to see a working RAID5/6 feature, but as it stands now it only supports RAID1/0/10. Too bad, would've considered it as a viable option to mdadm + BTRFS.
It said the code base was build on something stable, but it didn't say what, do you happen to know what FS this project is a fork of?
Currently I'm using bcachefs with LVM (which can do raid, but I currently only have one NVME SSD), though it indeed does have RAID1/0/10 support. But overall I expect it not to not make the same silly default choices as btrfs, such as not being able to start the system if a RAID1 component of your root filesystem is missing. And, supposedly, when the RAID5/6 becomes stable, it won't have the write hole problem.
It's based on bcache :) by the same author, but of course bcache is not really a file system but rather some kind of object storage layer for the purpose of caching slower block devices and absorbing write load.
Bcachefs might be coming soon to the mainline kernel, so that's going to make it a lot easier to try out. Personally however I have lost one bcachefs (that FS was readable, though, and I have good backups), but I have also lost a btrfs before and seen reiserfs bugs, so I don't too heavily count it against it; overall I enjoy its stability when using basic functionality. I haven't dared trying snapshots with it yet..
Nah, I got it set up on a P4 with a 20GB drive, takes about 2 or 3GB. As time progresses, older snapshots get deleted automatically by Timeshift 😉. So, say you got 4 daily set up, 4 weekly and 2 montly. Only the last 4 daily, 4 weekly and 2 monthly stay, the rest are deleted as new snapshots are created. That's the while point of having this setup, so you can go back in time, but you decide how long.
woah! this is amazing! thanks for the help!!!
NP, glad I could help 😉 👍.
Depends on your needs and if you want to include changes made to documents in home for example while you work during the day. For me the OS just does snapshotting when packages are updated so I can rollback if something breaks. The rest I do normal backups. because snapshotting is not backup if its on the same machine. Btrfs Send will let you push a snapshot elsrwhere though.