[lustre-devel] RFC: Spill device for Lustre OSD

[Oleg Drokin]

On Tue, 2025-11-04 at 23:07 +0000, Andreas Dilger via lustre-devel
wrote:
> 
> If we can implement a no-transaction osd-vfs, that would expose a
> lot of flexibility for other reasons as well.  Possibly the osd-vfs
> could
> implement a journal or other logging layer internally to make up for
> lack of transactions, whether initially or at a later stage?

That's actually an interesting idea, but probably not very practical.
The journal itself is probably not really feasible with VFS api alone
because you need to touch journal together with whatever it you are
modifying, unless you update the journal first and then everything
else, but that is likely going to be slow due to all the overhead?
That's probably why all the journaling filesystems hide the journal
inside themselves out of reach for the VFS api.
Of course VFS api could probably be extended eventually if there's a
good justification, but who knows how long it'll take and how the final
agreed upon implementation would actually look like.