[PATCH 0/3] yum-utils: fs-snapshot support for LVM snapshots

[PATCH 0/3] yum-utils: fs-snapshot support for LVM snapshots

[Mike Snitzer]

On Wed, Feb 03 2010 at  4:04pm -0500,
Chris Ball <cjb@laptop.org> wrote:

> Hi Mike,
> 
>    > It is my hope that these changes can still make F13 as part of
>    > the "System Rollback" feature.  The existing project Feature page
>    > could be extended to include LVM snapshot information:
>    > http://fedoraproject.org/wiki/Features/SystemRollbackWithBtrfs
>    
> Sounds fine to me.

What steps should we be taking now?

For starters we need to get rawhide's yum-utils updated to include the
latest fs-snapshot plugin updates that are now upstream.

Who should update the SystemRollbackWithBtrfs page?  Or should we create
a new SystemRollbackWithLvm page that is linked to from
SystemRollbackWithBtrfs?

> It'd be good to have your input on the gnome-disk-utility UI for
> snapshots too, now that we'll have more than one user for it -- we're
> discussing at:
> 
> https://bugzilla.gnome.org/show_bug.cgi?id=608204
> http://bugs.freedesktop.org/show_bug.cgi?id=26258

I'm open to helping answer any questions David might have, and making
any lvm changes needed to assist his effort, once he has time to look at
gnome-disk-utility's snapshot integration (via lvm and btrfs).

It would be nice if gnome-disk-utility knew to treat LVM snapshot LVs
that have a "yum_<date>" tag as being part of a "system rollback point"
or some such.  But I'm not sure of the best way for David to
programatically (or via lvm utility) access a snapshot LV's lvm tag(s).
A stop-gap would be to just rely on the suffix of the LV name to end
with: "_yum_<date>" (but that is fairly crude!)

Mike

[PATCH 0/3] yum-utils: fs-snapshot support for LVM snapshots

[David Zeuthen]

On Mon, 2010-02-08 at 09:40 -0500, Mike Snitzer wrote:
> > It'd be good to have your input on the gnome-disk-utility UI for
> > snapshots too, now that we'll have more than one user for it -- we're
> > discussing at:
> > 
> > https://bugzilla.gnome.org/show_bug.cgi?id=608204
> > http://bugs.freedesktop.org/show_bug.cgi?id=26258
> 
> I'm open to helping answer any questions David might have, and making
> any lvm changes needed to assist his effort, once he has time to look at
> gnome-disk-utility's snapshot integration (via lvm and btrfs).
> 
> It would be nice if gnome-disk-utility knew to treat LVM snapshot LVs
> that have a "yum_<date>" tag as being part of a "system rollback point"
> or some such.  But I'm not sure of the best way for David to
> programatically (or via lvm utility) access a snapshot LV's lvm tag(s).
> A stop-gap would be to just rely on the suffix of the LV name to end
> with: "_yum_<date>" (but that is fairly crude!)

I think some kind of "system restore/rollback point" functionality is a
good idea. 

I'm not sure, however, that Palimpsest should be the UI (it's a disk
utility, first and foremost) for this - it sounds like it might be
better to do a dedicated system-config-restorepoint program for this. I
don't know. That said, I think we still might want to display a list of
snapshots in Palimpsest for both LVM and btrfs - and with good naming
maybe that UI is good enough for rollback purposes and we don't need a
s-c-restorepoint. I don't know.

Regarding the LVM tags (which we'd also like to display and allow the
user to edit), I've already filed a bug asking for something like

 char **lvm_vg_get_tags(const vg_t vg);
 char **lvm_lv_get_tags(const lv_t lv);
 char **lvm_pv_get_tags(const pv_t pv);

in liblvm2app.

Thanks,
David

[PATCH 0/3] yum-utils: fs-snapshot support for LVM snapshots

[Chris Ball]

Hi,

   > I think some kind of "system restore/rollback point"
   > functionality is a good idea.
   > 
   > I'm not sure, however, that Palimpsest should be the UI (it's a
   > disk utility, first and foremost) for this - it sounds like it
   > might be better to do a dedicated system-config-restorepoint
   > program for this. I don't know. That said, I think we still might
   > want to display a list of snapshots in Palimpsest for both LVM
   > and btrfs - and with good naming maybe that UI is good enough for
   > rollback purposes and we don't need a s-c-restorepoint. I don't
   > know.

Ray Strode's suggestion was to please *not* create a new s-c utility
and instead look into Palimpsest.  :)

The argument for putting it in Palimpsest, which I'm quite convinced
by, is that this is a feature that's being exposed to userspace by
filesystems (btrfs will provide its own command-line interface), and
it's appropriate and useful for Palimpsest to provide a unified GUI
for filesystem operations.  It already does that for label-setting,
fsck, resize, and so on.  Switching or creating an active snapshot
becomes just another operation.

.. but I'm happy to take on creating a system-config-snapshots if it's
preferred -- it was actually part of the first version of the rollback
proposal, before we moved towards g-d-u instead.  (If we did go with
that, I think it would make sense to tell udisks about snapshot
management and then base it on that, perhaps with some new Python
bindings for the udisks dbus interface.  Make sense?)

Thanks,

- Chris.
-- 
Chris Ball   <cjb@laptop.org>
One Laptop Per Child