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Time Machine-style backups with rsync (2018)
- nightshift1 9mo agoSeems similar to https://rsnapshot.org/ https://rsnapshot.org/
- kunjanshah 9mo agoThis is the more robust way to go. Uses rsync under the hood.
- pmontra 9mo agoI've been using snapshot for backups since so many years that I forgot when I started. I keep the last 14 snapshots.
- mixmastamyk 9mo agoDoes rsnapshot do any of the hard thinking? Or just configures, then hands off to rsync?
- mrtesthah 9mo agoIsn’t restic better for backups overall? Anyone have a good script for macOS triggered by launchd, ideally something that uses FSEvents to check for directory changes?
- crossroadsguy 9mo agoYes, it is; among a few other great cross-platform FOSS tools that are built just for backups, and they do it really well. But most of them do periodic scans (as opposed to file change trigger-based backup runs, which I guess is what you might be looking for, I assume by your second sentence).
- mrtesthah 9mo agoFSEvents can be used for triggering a backup on change, but in the case of emulating their use in Time Machine, the goal is to use them to list all directories which have been changed since the last backup to avoid unnecessary rescanning.
- movetheworld 9mo agoI use restic, too, and I am very pleased with it, although I run it on windows, which works, but isn't perfect. So, you use it regularly?
- nine_k 9mo agoIf we spoke about a Linux box, one that prudently ran ZFS, or XFS on top of LVM, it would be possible to make a snapshot before the diffing and sending, so that the snapshot would be indeed point-in-time. IDK if whatever macOS uses for the filesystem supports snapshots. Otherwise, I think, restic or kopia are better for proper backups, and Syncthing for keeping a mirror copy. But the simplicity of this script in charming.
- wrs 9mo agoYes, APFS supports snapshots. [0] [0] https://support.bombich.com/hc/en-us/articles/20686443871383-Introduction-to-Snapshots https://support.bombich.com/hc/en-us/articles/20686443871383...
- sam_lowry_ 9mo ago> But the simplicity of this script in charming. An important feature of backups is the ability to restore them. As much as I love restic, I have at least one backup target with hard links.
- nine_k 9mo agoHave you ever faced a case when restic would not restore a backup? Or would not mount a remote backup? I have a mirror that Syncthing maintains, with some staggered versioning; it seems similar, and should help me immediately in a case of clobbering something. Restic backups helped me several times in cases of catastrophic failures, and are now the default way of moving my stuff to a new machine.
- orev 9mo agoThe original post that introduced this idea into general public: http://www.mikerubel.org/computers/rsync_snapshots/ http://www.mikerubel.org/computers/rsync_snapshots/ I’m sure others will chime in that they used hard links like this before then, however as noted in that page, it’s the one that made it popular enough that rsync was updated to support the idea natively.
- hughc 9mo agoI've been using a bash encapsulation of this for a long time, works great. https://github.com/laurent22/rsync-time-backup https://github.com/laurent22/rsync-time-backup
- EGreg 9mo agoWhy make hard links when you can use rsync or syncthing to just make an actual copy on an external hard drive eg via wifi or just remotely?
- kej 9mo agoThe hard links are to the most recent backup before the one happening now in the script, so that you aren't storing full copies of files that haven't changed between backups.
- c0nsumer 9mo agoHard links are file level dedupe. And then once all references to the inode are removed (by rotating out backups) it's freed. So there's no maintenance of the deduping needed, it's all just part of how the filesystem and --link-dest work together.
- 00deadbeef 9mo agoIt does make an actual copy but then it builds a directory structure that you can browse by date (like Time Machine). That directory contains hard links so only one copy of a file is ever backed up but you see contents that match the date of the backup.
- c0nsumer 9mo agoHa. That's a throwback. I did the same thing, but with a more detailed writeup, in 2009: https://nuxx.net/blog/2009/12/06/time-machine-for-freebsd/ https://nuxx.net/blog/2009/12/06/time-machine-for-freebsd/ It was really handy, but I now use borg as it just works better.
- human_llm 9mo agoHA! It read your post I read back then and I have been using it ever since. So thank you. I guess I need to check out borg ;)
- c0nsumer 9mo agoSmall world! You're welcome. Yeah, give borg a look. It's just faster to back up, faster to delete old backups, and just easier to do restores because so long as you have the appropriate credentials you can list the archive from any machine. I think there's still a place/use for --link-dst and hardlinks, but as a backup system I think borg does it better. For reference: https://nuxx.net/blog/2019/11/10/using-borg-for-backing-up-nuxx-net/ https://nuxx.net/blog/2019/11/10/using-borg-for-backing-up-n...
- theteapot 9mo agoNeed to combine this with LVM or BTRFS or similar to be a true snapshot. Rsnapshot supports LVM snapshot pretty good.
- fenazego 9mo agoOnce you have btrfs you don't really need rsync anymore, its snapshot + send/receive functionality are all you need for convenient and efficient backups, using a tool like btrbk.
- LeoPanthera 9mo ago"borg" has basically solved backups permanently. It's deduplicated, even across snapshots, compressed, and end-to-end encrypted. I'm surprised it's not more well known.
- locknitpicker 9mo ago> "borg" has basically solved backups permanently. It's deduplicated, even across snapshots, compressed, and end-to-end encrypted. Deduplication helps minimize space, but isn't it a major liability in backups? I mean, what happens when you try to restore your backups but a lone sector holding a file from way back in the past happens to not be recoverable? Doesn't it mean that no matter how frequent your backups are, your data is lost?
- NSUserDefaults 9mo agoIn that case you are supposed to use your /other/ backup. Which you have.
- DaSHacka 9mo agoDefeating the point of deduplication...
- homebrewer 9mo agoYou don't have backups if you only have one "backup". Look up sysadmin's 3-2-1.
- NSUserDefaults 9mo agoOn a single drive, deduplicate all you want. But you need to have two drives, at least, anyway.
- haradion 9mo agoIt doesn't really hurt in practice because it's only one part of the full backup procedure. Deduplicate to save space; re-duplicate the (smaller) backups to separate media for redundancy; scrub regularly for bit rot and rotate your media. A proper backup system requires all but the first of those anyway.
- hcartiaux 9mo agoI use bontmia since forever, based on the same rsync feature (link-dest for creating hard links to the unmodified files since the last backup). It also supports backup rotation and I think it's quite solid/reliable after all these years: https://github.com/hcartiaux/bontmia https://github.com/hcartiaux/bontmia
- mattbillenstein 9mo agorestic to s3 has been very reliable - haven't tried borg.
- nocman 9mo agosounds similar to rdiff-backup ( https://rdiff-backup.net https://rdiff-backup.net ). I know some folks that have been using that for a very long time as well.
- 00deadbeef 9mo agoReminds me of a tool I used to use that did a similar thing: https://github.com/jeremywohl/glastree https://github.com/jeremywohl/glastree
- cyberax 9mo agoOne big drawback of these solutions is that they cannot archive the system apps properly. Nor can they be used during the OS setup. TM integration is just so convenient...
- zimpenfish 9mo agoUsed this technique (albeit counter-based, not time-based) successfully for backing up the 2006 World Cup site newsfeed[0] configurations/data. Had 6 rotating backups on two hosts. Never had to use them (as best I remember) but it was definitely comforting to know they were there in case of urgent rollback. [0] Not strictly the right name but I've forgotten. Y!uk people of that era know what I mean.
- kunley 9mo agoIsn't it also how timeshift [1] backups are working? [1] https://github.com/linuxmint/timeshift https://github.com/linuxmint/timeshift
- deng 9mo agoThis is just half of what Time Machine does. What people are constantly missing is that Apple Time Machine is fast, as it does not need to walk through the whole filesystem to find changed files. Thanks to FSEvents, introduced in Mac OS X Leopard, it knows which directories actually contain changed files and hence usually only needs to check a small fraction of the filesystem. (Not sure if it still works that way after the switch to APFS). This would of course also be possible on Linux (using *notify), and there are some projects which try to do this, but it's really hard to do it reliably. You might argue that this feature is less important nowadays because NVME SSDs are so fast, but still, I remember very well how astonished I was that creating a new time machine snapshot on OS X Leopard took mere seconds.
- afandian 9mo agoI lost all my files to Time Machine in 2008. I don't remember exactly what happened. But since then I'll take a slightly slower, observable command-line copy over sparkly magic.
- lkuty 9mo agoYes, I do not trust TM. That's why I have both a backup with TM for convenience and also to have all the files (including system files), and a mirror of the important files (basically my home directory) with `rsync`.
- homebrewer 9mo agoNo, the right way to do this on Linux and FreeBSD is to use zfs with zfs send/receive. Creating snapshots and sending them is efficient enough to use it as the underlying storage for moderately loaded databases and VMs. They are atomic and require zero downtime. They can be encrypted and resent to other machines. Cloning whole machines from them is easy and efficient.
- amelius 9mo agoAnother thing Time Machine (hopefully) does is append-only backups.
- eternityforest 9mo agoI remember doing my own backups with rsync a super long time ago! It worked pretty well, but it didn't have compression, encryption, desktop integration, or deduplication, and adding anything would be one more script to maintain. Now I use Kopia, no real complaints there. I used to use Borg but until recently it needed some fussy extra community package to work on Synology.
- TKAB 9mo agoWhat happened to tarsnap? Anybody using it?
- cperciva 9mo agoIt's still there; and yes, people are using it.