Continuing with the theme of replacing drives, recently I decided to preemptively replace one of the external drives that I backup to via rsnapshot – or, more specifically, via cryptshot. The drive was functioning nominally, but its date of manufacture was 2014. That’s way too long to trust spinning rust.

rsnapshot implements deduplication via hard links. Were I to just rsync the contents of the old drive to the new drive without any special consideration for the links, it would dereference the links, copying them over as separate files. This would cause the size of the backups to balloon past the capacity of the drive. Rsync provides the --hard-links flag to address this, but I’ve heard some stories about this failing to act as expected when the source directory has a large number of hard links (for some unknown definition of “large”). I’ve been rsnapshotting since 2012 (after a pause sometime after 2006, apparently) and feel safe assuming that my rsnapshot repository does have a “large” number of hard links.

I also do not really care about syncing. The destination is completely empty. There’s no file comparison that needs to happen. I don’t need to the ability to pause partway through the transfer and resume later. Rsync is my default solution for pushing files around, but in this case it is not really needed. I only want to mirror the contents of the old drive onto the new drive, exactly as they exist on the old drive. So I avoided the problem all together and just copied the partition via dd.

Both drives are encrypted with LUKS, so first I decrypt them. Importantly, I do not mount either decrypted partition. I don’t want to risk any modifications being made to either while the copy is ongoing.

$ sudo cryptsetup luksOpen /dev/sda old
$ sudo cryptsetup luksOpen /dev/sdb new

Then I copy the old partition to the new one.

$ sudo dd if=/dev/mapper/old of=/dev/mapper/new bs=32M status=progress

My new drive is the same size as my old drive, so after dd finished I was done. If the sizes differed I would need to use resize2fs to resize the partition on the new drive.

If I was replacing the old drive not just because it was old and I was ageist, but because I thought it may be corrupted, I would probably do this with GNU ddrescue rather than plain old dd. (Though, realistically, if that was the case I’d probably just copy the contents of my other rsnapshot target drive to the new drive, and replace the corrupt drive with that. Multiple backup mediums make life easier.)

As previously mentioned, I use myrepos to keep local copies of useful code repositories. While working with backups yesterday I noticed that this directory had gotten quite large. I realized that in the 8 years that I’ve been using this system, I’ve never once run git gc in any of the repos.

Fortunately this is the sort of thing that myrepos makes simple – even providing it as an example on its homepage. I added two new lines to the [DEFAULT] section of my ~/library/src/myrepos.conf file: one telling it that it can run 3 parallel jobs, and one teaching it how to run git gc.

[DEFAULT]
skip = [ "$1" = update ] && ! hours_since "$1" 24
jobs = 3
git_gc = git gc "$@"

That allowed me to use my existing lmr alias to clean up all the git repositories. The software knows which repositories are git, and only attempts to run the command in those.

$ lmr gc

After completing this process – which burned through a lot of CPU – my ~/library/src directory dropped from 70 GB to 15 GB.

So that helped.

I noticed that my Borg directory on The Cloud was 239 GB. This struck me as problematic, as I could see in my local logs that Borg itself reported the deduplicated size of all archives to be 86 GB.

A web search revealed borg compact, which apparently I have been meant to run manually since 2019. Oops. After compacting, the directory dropped from 239 GB to 81 GB.

My borg wrapper script now looks like this:

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#!/bin/sh
source ~/.keys/borg.sh
export BORG_REPO='borg-rsync:borg/nous'
export BORG_REMOTE_PATH='borg1'

# Create backups
echo "Creating backups..."
borg create --verbose --stats --compression=lz4             \
    --exclude ~/projects/foo/bar/baz                        \
    --exclude ~/projects/xyz/bigfatbinaries                 \
    ::'{hostname}-{user}-{utcnow:%Y-%m-%dT%H:%M:%S}'        \
    ~/documents                                             \
    ~/projects                                              \
    ~/mail                                                  \
    # ...etc

# Prune
echo "Pruning backups..."
borg prune --verbose --list --glob-archives '{hostname}-{user}-*'   \
    --keep-within=1d                                                \
    --keep-daily=14                                                 \
    --keep-weekly=8                                                 \
    --keep-monthly=12                                               \

# Compact
echo "Compacting repository..."
backitup                                \
    -p 604800                           \
    -l ~/.borg_compact-repo.lastrun     \
    -b "borg compact --verbose"         \

# Check
echo "Checking repository..."
backitup -a                                                         \
    -p 172800                                                       \
    -l ~/.borg_check-repo.lastrun                                   \
    -b "borg check --verbose --repository-only --max-duration=1200" \

echo "Checking archives..."
backitup -a                                             \
    -p 259200                                           \
    -l ~/.borg_check-arch.lastrun                       \
    -b "borg check --verbose --archives-only --last 18" \

Other than the addition of a weekly compact, my setup is the same as it ever was.