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Linux is a family of open source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991 by Linus Torvalds. Linux is typically packaged in a Linux distribution (or distro for short).

Distributions include the Linux kernel and supporting system software and libraries, many of which are provided by the GNU Project. Many Linux distributions use the word "Linux" in their name, but the Free Software Foundation uses the name GNU/Linux to emphasize the importance of GNU software, causing some controversy.

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Automatic backups of inode tables and partition info for easier data recovery (lemmy.nz)

submitted 11 months ago* (last edited 11 months ago) by luthis@lemmy.nz to c/linux@lemmy.ml

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Good morning all, in today's episode of "What I learned during work hours"...

I was playing around with wxHexEditor and realised that if something catastrophic happened, I would really struggle with any data recovery if I lost the inode tables for any drive.

A quick duckle pointed me to e2image, which says in the man:

It is a very good idea to create image files for all file systems on a system and save the partition layout (which can be generated using the fdisk -l command) at regular intervals

at boot time, and/or every week or so.

I couldn't find any prebuilt solutions for this online, so I wrote a systemd service and timer to do this for me. I save the fdisk to a text file, run e2image on a couple drives, and compress it all together in a dated 7z that can get uploaded via rsync or Mega or Dropbox etc.

The metadata image from a 500gb drive is 8gb, but compresses down to 40mb. Backup takes a couple minutes.

~~Unfortunately this does not work with my raid drives, but they are RAID1 so already resilient.~~

Apparently I was being a derp somehow. ...Anyways,

My RAID drives are 16TB, e2image of this is 125gb, and 7z'd it comes down to just 63mb.

I'll post the service, timer, and backup script in a comment, let me know if you can spot anywhere for improvements!

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[–] lemmyvore@feddit.nl 2 points 11 months ago (1 children)

May I point out that all a RAID1 does is sync the blocks between two drives. It won't protect against writing something dumb that would mess up the filesystem, it will just dutifully sync it.

You should be able to back up ext data from a filesystem on a RAID array, unless I'm confused about what e2image actually does. Are you trying to use it on the underlying drive devices by any chance? You have to point it at the RAID device on top of them, something like /dev/md1 rather than /dev/sda1.

This sounds like a good extra backup to have but don't let it lull you into a false sense of security. It may help recover from a very specific kind of mistake but the recovery may be very specific as well. It's not file backup.

[–] luthis@lemmy.nz 1 points 11 months ago

Oh you're right it does work... well fuck knows what I was doing wrong before.

Yeah this is a backup in case I like, mv file to /dev/sda1 or something.

Not a backup of the files, but a backup of the structure.