Installation with multiple disks

Hi there.

First of all, please, forgive my ignorance of BTFRS volumes management.
Of course, I can and I will browse around to learn more, but I’d like your view on the strategy or direction to take first. I have not found a related post on this forum, but do not hesitate to point me towards if any; and apologies if such post does exist.

I have 4 disks (3 SSD and 1 HDD for backup) on my desktop computer. Garuda will be the only OS on this machine. UEFI installation.

I have thought about the following installation scheme: I use one SSD (nvme) to do the installation. I will mount the other disks later through fstab.

The questions I have:

  • Will it confuse snapper if I mount other disks later? What I have understood from BTRFS is it is useful to backup the system but the data can be backed up separately. Correct?
  • How to manage the home folder? Is it possible to connect the BTRFS home volume to another disk? Or is it possible to extend the home volume across 2 disks?
  • Or should I just mount /home on another disk and remove the BTRFS home volume?
  • Other options or recommendations?

Thanks for your insights.

No, only / will be used for snapper by default.

Perfect.

Use ln and forum search :slight_smile: I am busy IRL :wink:

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I usually format my non OS drives as ext4, then I symlink from them into my home directory.

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It will not “confuse” Snapper, but depending on what you are trying to achieve there may be additional configuration required. You have not specified what you want Snapper to do.

You may be conflating Btrfs with Snapper. The default Snapper configuration takes Btrfs snapshots of the root subvolume. You can add additional Snapper configs for any other subvolume you want to capture snapshots of–for example, your home subvolume or any other subvolumes you choose to set up.

As others have mentioned, an easy way to deal with this is to set up symlinks to other devices. This is simple and fast because you don’t really need to do anything but format the drives and fire off a couple commands to set up the symlinks.

However, if you choose to handle it this way you should bear in mind that nothing on those devices will be captured in the Btrfs snapshots of the subvolume they are symlinked from. When a snapshot is taken of a Btrfs subvolume, any symlinks within that subvolume are included as they are (i.e., as pointers to their target paths). The content that the symlink points to is not included in the snapshot.

You can add the other disks to the existing filesystem (Adding, removing and replacing devices in a Btrfs filesystem | Forza's Ramblings). Once the devices are combined into a single filesystem this way, you can snapshot the subvolumes as if they were a single device.

One of the nice things about combining the disks into a single device like this is subvolumes within the filesystem are able to expand to any size they need to be. For example, if you have two 1 TB disks and put the home subvolume on one and the root subvolume on the other, the maximum size of the home subvolume will obviously be 1 TB–even if the root subvolume only has 100 GB on it. If you combine the disks into a single filesystem, the home subvolume can continue to expand beyond the 1 TB. If root is only 100 GB then home could be up to 1.9 TB.

You can mount home on another device and just move the home subvolume over to the new device if you want to, so long as the extra device is also Btrfs. This is simple and easy to set up as well.

If you are setting up the disks as Btrfs, your options are pretty much unlimited because it is fairly trivial to move subvolumes hither and fro as you wish. You don’t need to feel like you are locked in to whatever configuration you decide to set up on the back of a fresh installation. Copy a subvolume over there, move it over here, rename it, make changes to it, copy it again, delete it, whatever–it’s all super easy once you get the hang of it.

My recommendations include:

  • Make backups as you go, and practice restoring the backups so when you actually need to you are prepared.
  • Experiment with the features. It’s a great way to learn!
  • Read the docs and forums when you have questions. There is a ton of material available for Btrfs, so you can go essentially as deep as you want to.
  • Have fun. :smile:
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Agree found BTRFS for secondary drives to be slow.

Thanks all for your prompt and thorough answers.

The most important for me was to make sure Snapper (as pointed out by @BluishHumility :wink:) will not try to make snapshots on everything and you confirmed it.

So, I just used 1 full disk with 1 partition to install Garuda.
Then, I just mounted the 3 others using part of the /etc/fstab I had before.
Everything works like a charm.
I will open a new thread to share my impressions after additional tweaks.

See you.

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