Re: [Networker] Does cloning unmuliplex and make recovery faster?

The answer is not necessarily, as that is not what we have seen in testing.

I used the GUI to clone a volume from like to like, and it de-multiplexed
it. Clone volume does just that. It works out all the savesets, and then
runs that nsrclone command.

Ask yourself this. No two tapes are not exactly the same length. To preserve
the original multiplexing, how would NetWorker achieve that?

Siobhan


On 18/1/07 6:40 AM, "Werth, Dave" <dave.werth AT GARMIN DOT COM> wrote:

> So basically it looks like when multiple SSIDs are specified in a single
> nsrclone command the relative multiplexing between those save sets will be
> preserved.  You can demultiplex it by specifying each SSID in a separate
> nsrclone command.
> 
> Dave
> 
> David Werth
> Garmin AT, Inc
> Salem, Oregon
> dave.werth<at>garmin.com
> 
> -----Original Message-----
> From: Curtis Preston [mailto:cpreston AT GLASSHOUSE DOT COM]
> Sent: Wednesday, January 17, 2007 11:19 AM
> To: NETWORKER AT LISTSERV.TEMPLE DOT EDU
> Subject: Re: [Networker] Does cloning unmuliplex and make recovery faster?
> 
> There are three possible scenarios of cloned data.  Which one of these
> scenarios happens to you will be based on how you clone:
> 1. A group of SSIDs that were mpx'd get completely de-mpx'd when they
> get cloned.
> 2. A group of SSIDs that were mpx'd stay mpx'd exactly the same when
> they're cloned.
> 3. A group of SSIDs that were mpx'd are partially de-mpx'd when they're
> the cloned.  
> 
> Remember that ALL cloning is saveset cloning, whether you're doing
> volume cloning (nsrclone -V <volume>), saveset cloning (nsrclone -S
> <SSID>), or automatic cloning (group level cloning).  In every scenario,
> nsrclone is given a list of one or more SSIDs to clone.  The only thing
> that determines whether or not something is de-multiplexed is how
> nsrclone was given the SSIDs.  Consider the following scenarios:
> 
> 1. Group level cloning.  Nsrclone is given a list of SSIDs from the
> backup that was just created.
> 2. Saveset cloning where nsrclone is given the name of a file with all
> the SSIDs to clone.
> 3. Saveset cloning where nsrclone is given a list of SSIDs on the
> command line.
> 4. Volume cloning where nsrclone is given the name of a volume to clone.
> 5. Saveset cloning where nsrclone is given only one SSID to clone.
> 
> Assume the following for the moment:
> 1. No SSIDs span tapes.
> 2. No other SSIDs are interleaved in with the SSIDs we want to clone.
> (e.g. no other backups were running at the same time from another group
> that we're not going to clone)
> 
> When scenario 1, 2, 3, or 4, nsrclone is given a list of SSIDs, and it
> clones them all, with mpx intact, and the cloned volume(s) will look
> exactly like the original volume(s).  You can verify this by looking at
> the offsets of the savesets on the tape.
> 
> When scenario 5 happens, however, it will de-mpx the tape, as it's only
> cloning one SSID.
> 
> Now, consider these additional scenarios:
> Scenario 1, 2 or 3 above where the list of SSIDs were interleaved with
> other SSIDs.  When this happens, obviously it's going to de-mpx a little
> bit, as you're not cloning all the same data.  But it's not going to
> completely de-mpx the data.  It's just not going to be mpx'd the same
> way the original was.
> 
> Scenario 4 where some SSIDs span that volume and go onto another volume.
> When this happens, the SSIDs that reside entirely on the volume will be
> mpx'd exactly the same.  However, when it starts cloning SSIDs that
> spanned to another volume, where or not they get somewhat de-mpxed will
> be based on whether or not they were mpxed with other SSIDs that are not
> getting cloned.
> 
> 
> ---
> W. Curtis Preston
> Author of O'Reilly's Backup & Recovery and Using SANs and NAS
> VP Data Protection
> GlassHouse Technologies
> 
> 
> -----Original Message-----
> From: networker-bounces AT backupcentral DOT com
> [mailto:networker-bounces AT backupcentral DOT com] On Behalf Of Fazil Saiyed
> Sent: Wednesday, January 17, 2007 5:56 AM
> To: NETWORKER AT LISTSERV.TEMPLE DOT EDU
> Subject: [Networker] Does cloning unmuliplex and make recovery faster?
> 
> There would have been easy way to find that out.
> Just look at original volumes and the savesets on them, then compare
> with 
> cloned tapes, you will have your answer, however, other post have
> indicated that there in no difference in cloning results wheather auto
> or 
> manual that it DOES Demultiplex. ( baring small saveset belew 100 mb).
> Either way, backing up to Disk and staging may be the cleanest and
> fastest 
> way to clone.
> Thanks
> 
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Siobhán

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