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!
Picture this: you open and edit one of your documents and save it.
The filesystem promptly allocates some blocks and updates the inodes. Maybe the inode table changed, maybe not. Repeat for some other files. Now your “inode backup” has a completely different picture of what is going on on your disk. If you try to recover the disk using it, all you will achieve is further corruption of the filesystem.