Re: COW/noCOW on MicroOS Desktop /home subvolume

On Mon, 2020-12-21 at 19:06 +0100, Dario Faggioli wrote:

Hello,

I've finally had the chance to put in a VM an instance of MicroOS Desktop with the new partition layout and. IMO, the fact that it has /var in a (nocow) subvolume is really a big improvement, so thanks Richard for that!

We have /home in a subvolume too, which is also great, and it as well has the nocow flag set. I know this mostly come from a conversation we had on #microos-desktop on IRC but thinking more about that, and discussing this with some users, I wonder whether it is really the best choice.

I mean, it sure is ok for /var, but for /home, using nocow means that we give up on some of the nicer BTRFS features, especially for home folders, wouldn't it?

That might be especially true for MicroOS Desktop. E.g., think at being able to compress (if not the entire home directories or the entire subvolume) the user installed flatpaks (and using that as an argument "against" those that are still complaining that > :-D).

So, are there reasons why it's really preferable to keep the /home subvolume as nocow and I'm missing them? Or shall we switch it to cow?

There's one, which is the main reason I did it in the first place GNOME Boxes (IMHO the best virtualisation tool) or virt-manager User Sessions puts qcow2 VM images in /home And in KDE there's database-like tools like akondi (sp?) with its datastore in /home

Also, while there, shall we evaluate adding other flags by default (i.e., things like autodefrag, or even compression itself)?

This is an interesting idea - but I'd rather we consider what makes sense for all of openSUSE there. I dont see MicroOS Desktop really bringing in unique requirements when it comes to autodefrag or compression.

E.g., AFAIUI, on Fedora, while not doing that right now, they're considering doing something like that, e.g.:

https://pagure.io/fedora-btrfs/project/issue/5

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