Restic on LTFS

Archiving to tape with restic: how I processed 414980 files, roughtly 60 GiB in about 10 minutes, with incremental updates too.

I’ve messed around with various solutions and this is just so simple and easy to use.

My hardware:

• …

using restic with ltfs: backup to an LTO drive the easy and fast way.

what im using

• server running 12 i think (debian)

why this combo?

• great way to do system snapshots! can store away. long shelflife.
• cheap per TB
• set and forget
• incremental updates
• encryption
• compression
• ease-of-use and simplicity: restic makes backups quick and painless, but also LTFS removes a lot of the headaches associated with managing tapes

what first?

• buy lto drive, maybe use sas connection

prepare ltfs

https://github.com/LinearTapeFileSystem/ltfs/blob/master/README.md

install and list ssci devices:

sudo apt-get install lssci
sudo lsscsi -g 

may not need above because ltfs -o device_list

pay close attention to what’s listed from command above.

install ltfs:

sudo wget https://mirrors.ustc.edu.cn/bjlx/pool/main/l/ltfs/ltfs_2.5.0.0~20240731-2_amd64.deb
sudo apt-get install ./ltfs_2.5.0.0\~20240731-2_amd64.deb

format the tape for ltfs or something:

sudo mkltfs -d /dev/st0 -f

note that for the above, you may want look at something like this (note that larger blocksizes may be optimal in some situations), depends on what your tape setup supports:

sudo mkltfs -d /dev/st0 --volume-name all-start-2024-11-18 --blocksize 1048576 -f

the above block size takes into account planned restic pack-size.

create the mount point:

sudo mkdir /mnt/tape

try mounting

sudo ltfs /mnt/ltfs -o devname=/dev/sg4

debugging ltfs

has good manpage.

check the ltfs:

sudo ltfsck /dev/st0

verify the mount status:

mount | grep ltfs

check what’s on the tape:

ls /mnt/ltfs

really test it out:

echo "test" >> /mnt/ltfs/test.txt
sudo umount /mnt/ltfs
sudo mt -f /dev/st0 eject
ls /mnt/ltfs

then try mounting again and checking the file.

restic

check out these tweaks:

https://restic.readthedocs.io/en/latest/manual_rest.html

from above i was sad to find that --read-concurrency is not available in the stable repo for debian as of right now (current restic verison is 0.14.x or whatever).

Prepare the restic repository:

sudo RESTIC_PASSWORD_FILE=/etc/restic-password /usr/bin/restic init -r /mnt/ltfs

To find what you should exclude you should exclude firstly, the things in Linux that don’t make much sense to me to backup (things like /proc), but also see what the largest files are, which may indicate which directories to ignore:

sudo find / -type f -exec du -h {} + | sort -rh | head -n 10

Here’s my command for backups, note the pack-size (chosen relative to LTFS block size), and be sure to exclude what you can (lowest hanging fruit, at least):

sudo RESTIC_PASSWORD_FILE=/etc/restic-password /usr/bin/restic backup / \
    --exclude /home/baudrillard/.bitmonero \
    --exclude /root/.bitmonero \
    --exclude /nix \
    --exclude /mnt \
    --exclude /tmp \
    --exclude /run \
    --exclude /var/tmp \
    --exclude /lost+found \
    --exclude /media \
    --exclude /sys \
    --exclude /usr/share/ollama/.ollama/models/blobs \
    --exclude /proc \
    --exclude /dev \
    -r /mnt/ltfs \
    --compression max \
    --pack-size 128

Pretty impressive speed for me:

processed 414986 files, 64.833 GiB in 11:22

Don’t forget to keep /etc/restic-password backed up, like in a password manager!

verify the backup:

sudo RESTIC_PASSWORD_FILE=/etc/restic-password /usr/bin/restic snapshots -r /mnt/ltfs

You can do a differential/incremental update by running the same backup command, but here I try adding over 1TB of data from my /media backup directories by simply running the backup command again, but removing /media from exclude.

Things to think about

handy debug:

sudo ltfsck /dev/sg4

If you interrupt a backup it’ll just totally mess up LTFS, I think.

make sure hardware compression is enabled?

Install this tool and check if compression:

sudo umount /mnt/ltfs
sudo apt install sg3-utils
sudo sginfo --all /dev/sg4

sudo mt -f /dev/st0 status
sudo mt -f /dev/st0 comp on
sudo mt -f /dev/st0 status

Original content in gopherspace: gopher://gopher.someodd.zip:70/0/phlog/ltfs-restic-backup-archives.gopher.txt