Hey Greg,

I'm sorry but that doesn't seem possible to me.  It would require huge
amounts of buffer space to make this happen.
Just think about it... if you had 4 sessions going to a backup volume,
and each session was a 40 GB saveset.  If you past a list to nsrclone
containing these 4 ssids it would either have to run through the tape 4
times, which it doesn't look like it occurs, and would then would get
around 1/4(maybe a little faster because it might be able to fsf through
some parts of the tape) of maximum drive speed during the clone process.
Or it would require at least 120GB of buffer space so it could read all
of them in one pass writing only one to tape and buffering the other 3
so they can then be written to the clone tape in contiguous format.  I
don't have 120GB of memory, and my disk can't push data at 30MB/s so I
can't see how the buffering would be occurring.

Does anyone know of a way to display the order and interleaving on a
specific piece of media?  I'd like to be able to see the order of the
saveset chucks.

Can someone explain where I'm going wrong in my thinking if it does
de-multiplex.

Thanks,

Joel


-----Original Message-----
From: Gregory Demilde - System Support Engineer
[mailto:Gregory.Demilde AT Sun DOT COM] 
Sent: Wednesday, April 23, 2003 8:46 AM
To: NETWORKER AT LISTMAIL.TEMPLE DOT EDU; Joel Fisher
Subject: Re: [Networker] Merits of cloning versus dual backups?

Joel

Clone tape are demultiplexed.

The reason why cloning can go fast and even faster than backup is
related to the 
fact the disks are not the bottleneck anymore. tape drive can sustain
transfer 
rates while disks are limited by IOPS.

Greg

| 
| Hmmmm.... I would think it would be impossible to get the clone speeds
| I'm getting if it is doing any type of de-multiplexing.  Still would
| like to hear for one of the Legato people on the list.
| 
| Joel
| 
| -----Original Message-----
| From: Tarjei T. Jensen [mailto:tarjei.jensen AT KVAERNER DOT COM] 
| Sent: Wednesday, April 23, 2003 7:50 AM
| To: NETWORKER AT LISTMAIL.TEMPLE DOT EDU
| Subject: Re: [Networker] Merits of cloning versus dual backups?
| 
| Joel Fisher wrote:
| >Then I believe the chunks on the clone tape will be:
| >
|
>[222...][222...][444...][222...][444...][222...][444...][666...][222...
| ]
| >[666...]
| >
| >I'd loved to hear a Legato person chime in here to verify or correct
| >what I'm saying?!?!
| 
| The story we have been told is that cloning untangles the savesets and
| optimizes them for recover.
| 
| greetings,
| 
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