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I have a laptop running Arch from a HDD, and hard-drive access is sometimes a bit slow. In particular, booting and starting a few programs (Firefox, LibreOffice) takes a while. To solve this, I thought I might install a small m.2 SSD and move my / partition to it (/home is already separate).
The simplest way to do this would be to install a 128gb or 256gb drive. Unfortunately, my laptop only supports 2242 m.2 drives, which means I'd be paying a premium for a low-quality drive of that size.
My solution is to use a "cache"-sized drive. Since quite a few people buy laptops with 16gb SSD caches and then upgrade them, I figure I can find one for a lower price. But this leads to the issue of size, since my / partition is currently a bit over 17gb.
My idea is to separate out the largest parts of /usr/lib and /usr/share that aren't needed on boot, and to put them on the larger HDD instead. They would then be mounted at the same time as /home. How practical would this be?
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What about /var, is that already on a separate partition? Usually this takes some GB and it makes much sense to have this as a separate partition. Also some people end up with large stuff installed in /opt (often from AUR packages or manual installs).
Otherwise your approach should work, but might get a little bit complicated since you only want some things of /usr/share or /usr/lib moved. If I look into my folders there are not many subfolder there that really make a difference in disk usage, so you likely end up having a lot of symlinks (or mount points, but that's even more cumbersome) you have to manage manually. That likely will cause you trouble and extra work when performing package installs.
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That makes sense. /opt is 2.4gb, /var is 1gb, so they would make a difference but not a huge one. It sounds like that would be more trouble than it's worth.
What about btrfs with compression? I've seen some impressive numbers with that.
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That makes sense. /opt is 2.4gb, /var is 1gb, so they would make a difference but not a huge one. It sounds like that would be more trouble than it's worth.
That at least would help to make your current data fit on 16 GB (according to your comment you should end up with around 14GB used). And /var can grow much larger, especially /var/cache/pacman (unless you already put that on a separate partition) and to some extend /var/log, so I recommend putting this on a separate partition in any case. I give it always around 8GB which works quite well for me. The rest of the file system (except /home of course) usually doesn't grow much more unless you need to install large software packages. Just make an estimate on what you think you will install.
What about btrfs with compression? I've seen some impressive numbers with that.
No experience with disk compression and what savings you can expect. But given the sizes it should help.
Maybe also have a look what software you have installed that takes up the 14 GB. That's really a lot, and probably you can save some space just by uninstalling unused software. The thread at https://bbs.archlinux.org/viewtopic.php?id=36529 could help in finding the largest installed packages.
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bcachefs has been merged into the linux kernel, that may be a solution to your problem
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