Re: HSM (was Re: [malware-list] TALPA - a threat model? well sorta.)

[Pavel Machek]

On Tue 2008-08-19 12:10:32, Rik van Riel wrote:
> On Tue, 19 Aug 2008 09:14:16 +0200
> Pavel Machek <pavel@xxxxxxx> wrote:
> 
> > On Mon 2008-08-18 12:43:39, Rik van Riel wrote:
> > > On Mon, 18 Aug 2008 16:33:13 +0100
> > > Alan Cox <alan@xxxxxxxxxxxxxxxxxxx> wrote:
> > > 
> > > > > 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 :)
> > 
> > But is this really needed to be cross-filesystem thing? I'd expect
> > this to be implemented with FUSE, maybe FUSE+unionfs...
> 
> If you think FUSE+unionfs is a cleaner solution than one
> hook in the VFS, I've got a bridge to sell you.

If you can do it with one clean enough hook, I'll buy that bridge.

[If you want to do 'list directory before files are there' -- and you
seem to want to from description above -- fuse seems like a way to
go.]
							Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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