[Sheepdog] [PATCH 0/6] merge sheep and puppy into one sheepdog daemon, collie

[FUJITA Tomonori]

On Wed, 2 Dec 2009 19:05:15 +0000
Chris Webb <chris at arachsys.com> wrote:

> Incidentally, I had assumed the requirement for btrfs is because you use
> BTRFS_IOC_CLONE for copy-on-write behaviour to get cheap atomic updates in
> the same way I was doing in my block store. I can't see this being called at
> any point in store.c though. Which btrfs features are we actually using in
> sheepdog at the moment?

We need the data of a single write system call to be applied to a
super object in the "all or nothing" way (I assume BTRFS does but it
does not?).

We don't need to update multiple objects (files) stored on a single
machine atomically for now (I assume we can use BTRFS_IOC_TRANS_START
for this).

I guess that it takes some time until BTRFS matures so we've been
thinking about other options. One is using Berkeley DB for a super
object.