zfs discuss - Mar 2010 - ZFS+CIFS: Volume Shadow Services, or Simple Symlink?

> > ZFS+CIFS even provides
> > Windows Volume Shadow Services so that Windows users can do this on
> > their own.
> 
> I''ll need to look into that, when I get a moment.  Not familiar
with
> Windows Volume Shadow Services, but having people at home able to do
> this
> directly seems useful.
 

Even in a fully supported, all-MS environment, I''ve found the support
for
"Previous Versions" is spotty and sort of unreliable at best.  Not to
mention, I think the user interface is just simply non-intuitive.

 

As an alternative, here''s what I do:

ln -s .zfs/snapshot snapshots

 

Voila.  All Windows or Mac or Linux or whatever users are able to easily
access snapshots.

 

It''s worth note, in the default config of zfs-auto-snapshot, the snaps
are
created with non-cifs compatible characters in the filename (the ":"
colon
character in the time.)  So I also make it a habit during installation, to
modify the zfs-auto-snapshot scripts, and substitute that character.

-------------- next part --------------
An HTML attachment was scrubbed...
URL:
<http://mail.opensolaris.org/pipermail/zfs-discuss/attachments/20100320/15bcf335/attachment.html>

On Mar 19, 2010, at 9:25 PM, Edward Ned Harvey wrote:
> > > ZFS+CIFS even provides
> > > Windows Volume Shadow Services so that Windows users can do this
on
> > > their own.
> >
> > I''ll need to look into that, when I get a moment.  Not
familiar with
> > Windows Volume Shadow Services, but having people at home able to do
> > this
> > directly seems useful.
>  
> Even in a fully supported, all-MS environment, I?ve found the support for
?Previous Versions? is spotty and sort of unreliable at best.  Not to mention, I
think the user interface is just simply non-intuitive.
>  
> As an alternative, here?s what I do:
> ln -s .zfs/snapshot snapshots
>  
> Voila.  All Windows or Mac or Linux or whatever users are able to easily
access snapshots.
Clever.

Just one minor problem though, you''ve circumvented the reason why the
"snapdir"
property defaults to "hidden."  This probably won''t affect
clients that understand
symlinks, but IIRC, Windows doesn''t.  Hopefully, the Windows clients
will not try
to run backup programs themselves and will rely on server-side backups :-)
 -- richard

ZFS storage and performance consulting at http://www.RichardElling.com
ZFS training on deduplication, NexentaStor, and NAS performance
Las Vegas, April 29-30, 2010 http://nexenta-vegas.eventbrite.com

> > ln -s .zfs/snapshot snapshots
> >
> > Voila.  All Windows or Mac or Linux or whatever users are able to
> easily access snapshots.
> 
> Clever.
> 
> Just one minor problem though, you''ve circumvented the reason why
the
> "snapdir"
> property defaults to "hidden."  This probably won''t
affect clients that
> understand
> symlinks, but IIRC, Windows doesn''t.  Hopefully, the Windows
clients
> will not try
> to run backup programs themselves and will rely on server-side backups
> :-)
There''s no problem with the symlink being followed by CIFS clients,
including windows.  It just appears as if it''s a normal directory that
you
can look inside.

If anybody were trying to backup the ZFS root directory via CIFS, and
didn''t
have the ability (or intelligence) to exclude the snapshots directory, sure
it could be a problem.  But I certainly know I don''t have that problem.
I
promise you will never catch me creating backups of ZFS via CIFS.  ;-)

On Sun, Mar 21, 2010 at 08:59:29PM -0400, Edward Ned Harvey
wrote:
> > > ln -s .zfs/snapshot snapshots
> > >
> > > Voila.  All Windows or Mac or Linux or whatever users are able to
> > > easily access snapshots.
Not being a CIFS user, could you clarify/confirm for me..  is this
just a "presentation" issue, ie making a directory icon appear in a
gooey windows explorer (or mac or whatever equivalent) view for people
to click on?  The windows client could access the .zfs/snapshot dir
via typed pathname if it knows to look, or if it''s made visible, yes?

Otherwise, is there some other limitation because of the pathname
starting with dot that prevents this, which the symlink works around? 
> There''s no problem with the symlink being followed by CIFS
clients,
> including windows.  It just appears as if it''s a normal directory
that you
> can look inside.
> 
> If anybody were trying to backup the ZFS root directory via CIFS, and
didn''t
> have the ability (or intelligence) to exclude the snapshots directory, sure
> it could be a problem.  But I certainly know I don''t have that
problem.  I
> promise you will never catch me creating backups of ZFS via CIFS.  ;-)
Never say never..

--
Dan.
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 194 bytes
Desc: not available
URL:
<http://mail.opensolaris.org/pipermail/zfs-discuss/attachments/20100322/219d46c4/attachment.bin>

> Not being a CIFS user, could you clarify/confirm for me..  is this
> just a "presentation" issue, ie making a directory icon appear in
a
> gooey windows explorer (or mac or whatever equivalent) view for people
> to click on?  The windows client could access the .zfs/snapshot dir
> via typed pathname if it knows to look, or if it''s made visible,
yes?
You are correct.  A CIFS client by default will not show the "hidden"
.zfs
directory, but if you either click the checkbox "show hidden files"
then
you''ll see it, or if you type it into the addressbar, then you can
access
it.

However, my users were used to having a hidden ".snapshots" directory
in
every directory.  I didn''t want to tell them "You have to go to
the parent
of all directories, and type in .zfs" mostly because they can''t
remember
"zfs" ... So the softlink just makes it visible and easy to remember.
> > I
> > promise you will never catch me creating backups of ZFS via CIFS.  ;-
> )
> 
> Never say never..
Hehehehe.  Given the alternatives, I think this is a safe one.  I will never
backup a ZFS filesystem via CIFS client.  ;-)