From: Colm MacCárthaigh (colmmacc at domain redbrick.dcu.ie)
Date: Sat 14 Sep 2002 - 12:27:12 IST
On Fri, Sep 13, 2002 at 08:01:35PM -0700, Rick Moen wrote:
> One problem with e-mail is that you couldn't hear the doubtful tone as I
> pronounced, "Well, there is this stuff", in my head. ;->
> I thought it worth mentioning just in case it motivated someone to
> resume code maintenance.
> [Mountain View Data page:]
> > That's a NAS, that page does not even mention the word linux,
> > though it does mention ext2 as one filesystem it supports. I know
> > of many NAS's that support snapshots.
> It does run on Linux, though. The firm employs Peter Braam (the
> Intermezzo guy), and was founded by Cliff and Iris Miller after they
> lost control of TurboLinux, Inc.
> I didn't check the licensing, cost, or other details. It might be
> feasible to use just the snapshotting code.
I took a look at the snapfs code, it's a terrible approach, they
basically re-implement the VFS code as a VFS. You mount
a snapshoted filesystem as snapfs, which takes all of the calls
and then "proxies" them to the real fs. Maintaining it would be
a nightmare, you'd have to constantly replicate new VFS features.
Note , I'm not even talking about mounting a snapshot here,
just the filesystem you want to snapshot. It didnt even work with
non-ext2 stuff, crazy.
For snapshots to work, it needs to be on the roadmap for the kernel
and the VFS needs to be modified so that it can fire off the incremental
data somewhere else. The FreeBSD people are in the proccess of doing
this. The solaris people did it a long time ago. It's a feature
sorely lacking from linux and it doesnt look any progress is being
-- colmmacc at domain redbrick.dcu.ie PubKey: colmmacc+pgp at domain redbrick.dcu.ie Web: http://devnull.redbrick.dcu.ie/
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