On Mon, 18 Aug 2008 16:33:13 +0100
Alan Cox <alan@lxorguk.ukuu.org.uk> wrote:

quoted text
> > I could probably buy that, but I don't know how an HSM would work.
> > Would we have everything we need at open for them to fire off?
> > 
> > /me is HSM clueless and trying to include their needs is proving a
> > challenge.
> 
> So don't bother. Its a theoretical use for the most part so we can
> mangle the interface later. 

Think of a consumer HSM application: backup to rsync.net
or Amazon S3.

Instead of waiting for the whole backup to be restored,
you can start using the filesystem immediately.  The 
block-on-open hook can be used by the restore program
to fetch files from the remote backup site on an
as-needed basis, with a full restore going on in the
background.

If the block-on-open hook can be used for that (even
with additional magic, like creating empty HSM inodes
with a special attr to notify "the data lives elsewhere"),
HSM should be good.

The "data lives elsewhere" bit/xattr/whatever could also
be used on directories, so not even the whole directory
tree would have to be restored right on restore :)

-- 
All rights reversed.
--
unsubscribe notice
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/