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!

  • ∟⊔⊤∦∣≶OP
    3•6 months ago

    The script takes the drives as arguments:

    $ pwd
/usr/lib/systemd/system
$ cat drive_backup.service 
[Unit]
Description=backup fdisk + e2image
Wants=drive_backup.timer

[Service]
Type=oneshot
ExecStart=/usr/bin/backup_meta_data.sh /dev/sdc1 /dev/sdb1

[Install]
WantedBy=multi-user.target

    Set to run at 3:40am every day, but probably could be once weekly really.

    $ cat drive_backup.timer 
[Unit]
Description=timer to run drive backup
Requires=drive_backup.service

[Timer]
Unit=drive_backup.service
OnCalendar=*-*-* 03:40:00

[Install]
WantedBy=timers.target

    Should be fairly self-explanatory. 

    $ cat /usr/bin/backup_meta_data.sh
#!/bin/bash

working_dir=/home/st/drive_recovery/working
backup_dir=/home/st/drive_recovery
backup_date=$(date +%Y%m%d-%H%M)

mkdir -p $working_dir

sudo fdisk -x > $working_dir/$backup_date.fdisk

for var in "$@"
do
	clean=$(echo $var | sed 's;/;-;g')
	sudo e2image $var $working_dir/$backup_date.$clean
done

sudo 7z a $backup_dir/$backup_date.archive $working_dir/"$backup_date"*
sudo rm $working_dir/"$backup_date"*