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A new guide to archving with LTO5 and Debian.
I’ve found tapes are just best to write once and forget about it. Trying to do updates over time is kind of a pain and I’ve found it unreliable in some ways.
I have an exteranl LTO5 drive: HPE StorageWorks LTO-5 Ultrium 3000 SAS.
Install stunnel and stenc:
sudo apt-get update
sudo apt-get install stunnel stenc
Generate key (max is 256 bits):
sudo stenc -g 256 -k /etc/2024-11-lto5.key -kd "November 2024 LTO5 Tape Key"
Turn on encryption:
% sudo stenc -a 1 -f /dev/st0 -e on -k /etc/2024-11-lto5.key --protect
Provided key length is 256 bits.
Key checksum is 1a1c.
Turning on encryption on device '/dev/nst0'...
Success! See '/var/log/stenc' for a key change audit log.
At this point I noticed the blue encryption indicator lit up on my LTO5 drive.
Compression
I think compression is enabled by default.
Look up the compression page:
baudrillard@simulacra ~ % sudo sg_logs -p 0x32 /dev/sg4
HP Ultrium 5-SCSI Z3ED
Data compression page (LTO-5 specific) [0x32]
Read compression ratio x100: 114
Write compression ratio x100: 0
Megabytes transferred to server: 4
Bytes transferred to server: 129839
Megabytes read from tape: 3
Bytes read from tape: 633400
Megabytes transferred from server: 0
Bytes transferred from server: 0
Megabytes written to tape: 0
Bytes written to tape: 0
I’m going to use software compression, though.
Making the archive
Choose between zstd (faster) and xz (better compression ratio), but both
are built for streams, I think.
sudo tar \
--exclude=/home/baudrillard/.bitmonero \
--exclude=/root/.bitmonero \
--exclude=/nix \
--exclude=/snap \
--exclude=/var/cache \
--exclude=/mnt \
--exclude=/tmp \
--exclude=/media \
--exclude=/run \
--exclude=/var/tmp \
--exclude=/lost+found \
--exclude=/sys \
--exclude=/usr/share/ollama/.ollama/models/blobs \
--exclude=/proc \
--exclude=/dev \
--totals --checkpoint=100 --checkpoint-action=dot \
--use-compress-program="zstd" -cvf /dev/st0 /
This is crazy fast. But if blocking factor is large you’ll run out of space quickly. The solution is to perhaps place a single archive onto the tar.
Tips
- Tapes will like just writing one big file–so don’t be afraid to just slap a highly compressed archive onto there. It might be fun for me to show how to zpaq to tape, especially incrementally. Or using restic?
- Bigger block sizes and such for larger data
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