zfs discuss - Nov 2005 - Shadow copy format for snapshots and Samba

Samba has a shadow_copy module to serve read-only snapshots to windows clients. 
I tried to use snapshotting in freebsd 5 (haven''t tried 6), but
couldn''t get it stable.  I''m really looking forward to getting
it going on Solaris.

Anyway you can read about the format of the link here:
http://us5.samba.org/samba/docs/man/Samba-HOWTO-Collection/VFS.html#id2618182

When it was working on FreeBSD, it was really slick and windows users could
right-click and see the previous versions.

Anyway the idea is simple -- add an option "shadowcopylinks" to zfs,
and when a snapshot is created (and snapdir==visible), then do a symlink(? --
maybe something lower) from the .zfs/snapshot/snapname to @GMT-$time (time
format documented in the above link -- and it must be GMT).

Of course the symlink/whatever would get removed when the snapshot is removed.

If we had that and auto snapshotting like 2 at 30m, 2 at 12h, 7 at 1d, 4 at 1w
(take a snapshot every 30 minutes and keep the last 2, etc) -- I would be in
heaven.

Oh and I don''t think I have said "Thank you" or could say it
enough for zfs -- I''m so excited!

Anyone want to start an OpenSolaris file serving distro?  Bare minimum with
kernel, zfs, nfs, and samba (and libs...) -- small enough to be on a compact
flash.  I''ve done it with linux and the *bsd''s, but I
don''t know how long it would take to get up to speed on opensolaris.

jebc-devnull at c4solutions.net (remove the dev null and dash)
This message posted from opensolaris.org

On Sat, Nov 19, 2005 at 09:10:06PM -0800, Jeb Campbell
wrote:
> Samba has a shadow_copy module to serve read-only snapshots to windows
> clients.  I tried to use snapshotting in freebsd 5 (haven''t tried
6),
> but couldn''t get it stable.  I''m really looking forward
to getting it
> going on Solaris.
> 
> Anyway you can read about the format of the link here:
>
http://us5.samba.org/samba/docs/man/Samba-HOWTO-Collection/VFS.html#id2618182
> 
> When it was working on FreeBSD, it was really slick and windows users
> could right-click and see the previous versions.
> 
> Anyway the idea is simple -- add an option "shadowcopylinks" to
zfs,
> and when a snapshot is created (and snapdir==visible), then do a
> symlink(? -- maybe something lower) from the .zfs/snapshot/snapname to
> @GMT-$time (time format documented in the above link -- and it must be
> GMT).
I assume you mean create a symlink from:
	/data/shadow_share/@GMT-$SNAPNAME
to:
	/path/.zfs/snapshot/$SNAPNAME

after creating the snapshot?
> Of course the symlink/whatever would get removed when the snapshot is
removed.
> 
> If we had that and auto snapshotting like 2 at 30m, 2 at 12h, 7 at 1d, 4 at
1w
> (take a snapshot every 30 minutes and keep the last 2, etc) -- I would
> be in heaven.
Certainly sounds possible.

Cheers,
- jonathan

-- 
Jonathan Adams, Solaris Kernel Development

> I assume you mean create a symlink from:
> 	/data/shadow_share/@GMT-$SNAPNAME
> to:
> 	/path/.zfs/snapshot/$SNAPNAME
> 
> after creating the snapshot?
> 
> > Of course the symlink/whatever would get removed
> when the snapshot is removed.
(Not a kernel or filesystem dev as I''m sure you can tell...)
I hesitated to say symlink, because what happens when you rename the snapshot? 
Would something lower level in zfs be more appropriate?

> > If we had that and auto snapshotting like 2 at 30m,
> 2 at 12h, 7 at 1d, 4 at 1w
> > (take a snapshot every 30 minutes and keep the last
> 2, etc) -- I would
> > be in heaven.
> 
> Certainly sounds possible.
It would take some thinking to make it elegant enough for solaris standards...
Just trying to get the idea out there -- it would be a combination of cron and
logrotate ;)
This message posted from opensolaris.org