QUESTION : Why use a btrfs blank snapshot instead of tmpfs ? about nix-config HOT 9 OPEN

Hello!

I'm actually considering moving back to ext4+tmpfs, because of simplicity mostly.

Btrfs does have a couple of goodies that might make it worth using:

• Snapshots: useful to have lightweight "backups" (for human error situation, that is) for your data
• Transparent compression: shaves off about 20-30% storage with negligible performance impact
• Subvolumes: you can have logical volumes within the same physical partition, making it pretty painless to organize stuff into different mountpoints if needed

from nix-config.

My issue with tmpfs is that you have to specify a size for the tmpfs root or be limited based on your RAM. Tmpfs defaults to half your system RAM (I believe). Some guides set tmpfs to 2GiB (example), but that means that you can only have up to 2GiB of files on root outside of the files you have persisted on a separate partition. Btrfs' logical volumes avoid this by having automatically resizing subvolumes so I never have to think about the size of individual subvolumes.

from nix-config.

I have been using tmpfs for a while, and to be honest it has its quirks, see for example nix-community/impermanence#124 . This issue is not present when root is on btrfs.

from nix-config.

(sorry for the open and close, was answering from my phone)

I'm actually considering using both : tmpfs as root and everything else on btrfs. I found this blog post and I think I'll go this way

from nix-config.

would https://github.com/nix-community/disko not help with the "its complicated" part? didn't checked it out yet.

from nix-config.

would https://github.com/nix-community/disko not help with the "its complicated" part? didn't checked it out yet.

Didn't checked it out either. I've seen it mentioned on the forum but i don't want to mess with it now. Maybe later

from nix-config.

would https://github.com/nix-community/disko not help with the "its complicated" part? didn't checked it out yet.

Disko is pretty cool. Moving my setup to it is definitively on my todo-list.

from nix-config.

(sorry for the open and close, was answering from my phone)

I'm actually considering using both : tmpfs as root and everything else on btrfs. I found this blog post and I think I'll go this way

Nice post! Wish I'd found it sooner!
No really, I went with btrfs because it's really cool, I could make a raid with it without LVM it has compression (really 0 performance decrease with raid0) and...COW! ;)
Plus yeah some snapshotting for backup purposes do no harm I guess! ;) not to /nix of course, but /home and maybe /persist (especially when I'll wipe out even home at boot - the original post doesn't but I'll go for it once my home-manager configuration is really solid).

from nix-config.

My issue with tmpfs is that you have to specify a size for the tmpfs root or be limited based on your RAM. Tmpfs defaults to half your system RAM (I believe). Some guides set tmpfs to 2GiB (example), but that means that you can only have up to 2GiB of files on root outside of the files you have persisted on a separate partition. Btrfs' logical volumes avoid this by having automatically resizing subvolumes so I never have to think about the size of individual subvolumes.

That I didn't know and if it's true it really sucks because I'm already using zram xD.

from nix-config.