Who cares about multiplexed savesets!  What matters for speeding
recovery is de-multiplexing clients.

nsrclone will attempt to make one pass over the source tape.  Savesets
will remain multiplexed.  If you have multiple clients their savesets
will be multiplexed along with everything else.  That's where the speed
comes from in doing the original backup.  That's where the lack of speed
comes from in doing the restore.

If you have a critical client that must be restored quickly, clone it's
savesets with a single nsrclone command.  All of it's savesets will be
placed together on the clone tape.  Those savesets will still be
multiplexed together, but WHO CARES.  They all have to be restored to
recover the machine.  If you really care about the speed of restoring a
particular saveset, clone it first to get it de-multiplexed from
everything else.

Backups and clones are optimized for getting data onto the tape.  They
are not optimized for getting it off.



---
Jim McAlarney                                         Huber Engineered
Materials
phone:  404-949-5505                              4401 Northside
Parkway
fax:       404-949-1305                              Suite 600
jmcalarney AT huber DOT com                            Atlanta, GA  30327

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--- Begin Message ---

Subject:	Re: Merits of cloning versus dual backups?
From:	Kit Cunningham <kc AT IT-ASSIST.CO DOT NZ>
Date:	Thu, 24 Apr 2003 11:02:46 +1200

Thanks for that Terry.

Further questions if I may ask.

When I script using nsrclone I use
    mminfo (query here generating ssid's )  |nsrclone (options) -
i.e reading from stdin.
My view of the behaviour seen implies this will demultiplex the data.
Is this correct?


Also will nsrclone -f file demultiplex or not?

If I can modify the scripts used to not demulitplex I can see many happy
clients.

Kit


On 23 Apr 2003 at 14:49, Terry Clayton wrote:

> After checking a couple of internal Legato sources to be quite certain
the
> algorithm is as follows...
>
> nsrclone SSID1, SSID2, SSID3.....SSIDX  will move data from the source
to
> the target without any change to the data and no tape thrashing.....
>
> If a tape has 4 savesets interleaved, the data chunks are moved
> in order and laid down exactly without any de-deinterleaving - and
then
> re-interleaving the data.
>
> If you want to de-interleave the data then:
>
>          nsrclone SSID1
>          nsrclone SSID2
>          nsrclone SSID3
>          nsrclone SSID4
>
> In this case the data is read and written one save set at a time
> and the source  tape is repositioned accordingly, while the target
tape
> device has the savesets sequentially written. and of course it takes 4
times
> as long to complete than the previous case.
>
> > -----Original Message-----
> > From: Kit Cunningham [mailto:kc AT IT-ASSIST.CO DOT NZ]
> > Sent: Wednesday, April 23, 2003 2:31 PM
> > To: NETWORKER AT LISTMAIL.TEMPLE DOT EDU
> > Subject: Re: [Networker] Merits of cloning versus dual backups?
> >
> >
> > I just ran scanner -v over one of my clone volumes. My
> > reading of the information given is the
> > savesets are multiplexed. See below. (Solaris, v6.1.1 networker)
> >
> > I also see the the unexpected end messages mentioned in
> > another post. (This tape is a good
> > tape.) These seem to cause a repeated E(nd) message for that
saveset.
> >
> > A myth shatterred perhaps?
> > Hello legato people - Someone want to comment on this?
> >
> > Kit
> >
> >
> > .......................
> > scanner: ssid 392871937: found beginning of l4f:SYSTEM STATE:\
> > scanner: ssid 392866817: found beginning of u4f:/
> > scanner: scanning file 2, record 100
> > scanner: ssid 392877825: found beginning of 4f:C:\
> > scanner: scanning file 2, record 200
> > scanner: scanning file 2, record 300
> > l4f          SYSTEM STATE:\      12/13/01  3:44  f   6395896     10
> > 392871937 E
> > scanner: scanning file 2, record 400
> > scanner: scanning file 2, record 500
> > scanner: scanning file 2, record 600
> > scanner: ssid 392887297: found beginning of l4f:REPAIRDISK:\
> > scanner: ssid 392871937 unexpected end
> > l4f          SYSTEM STATE:\      12/13/01  3:44  f   6395896     10
> > 392871937 E
> > l4f          REPAIRDISK:\        12/13/01  3:45  1         4      0
> > 392887297 E
> > scanner: scanning file 2, record 700
> > scanner: scanning file 2, record 800
> > scanner: ssid 392891905: found beginning of l4f:C:\
> > scanner: scanning file 2, record 900
> > scanner: scanning file 2, record 1000
> > scanner: ssid 392887297 unexpected end
> > l4f          REPAIRDISK:\        12/13/01  3:45  1         4      0
> > 392887297 E
> > scanner: scanning file 2, record 1100
> > 4f           C:\                 12/13/01  3:48  1  25177520    529
> > 392877825 E
> > scanner: scanning file 2, record 1200
> > scanner: ssid 392913665: found beginning of
> > u4f:index:b1b7cd75-00000004-
> > 3af63b2e-3af63b2c-00030000-c6060614
> > scanner: ssid 392877825 unexpected end
> > 4f           C:\                 12/13/01  3:48  1  25177520    529
> > 392877825 E
> > u4f
> > index:b1b7cd75-00000004-3af63b2e-3af63b2c-00030000-c6060614
> > 12/13/01  3:36  1    295848     11 392913665 E
> > scanner: scanning file 2, record 1300
> > scanner: scanning file 2, record 1400
> > scanner: ssid 392913665 unexpected end
> > u4f
> > index:b1b7cd75-00000004-3af63b2e-3af63b2c-00030000-c6060614
> > 12/13/01  3:36  1    295848     11 392913665 E
> > u4f          /                   12/13/01  3:33  1   5168940    206
> > 392866817 E
> > scanner: scanning file 2, record 1500
> > scanner: scanning file 2, record 1600
> > scanner: scanning file 2, record 1700
> > scanner: scanning file 2, record 1800
> > scanner: scanning file 2, record 1900
> > scanner: scanning file 2, record 2000
> > scanner: scanning file 2, record 2100
> > scanner: ssid 392866817 unexpected end
> > u4f          /                   12/13/01  3:33  1   5168940    206
> > 392866817 E
> > scanner: scanning file 2, record 2200
> > scanner: scanning file 2, record 2300
> > scanner: scanning file 2, record 2400
> > scanner: scanning file 2, record 2500
> > scanner: scanning file 2, record 2600
> > scanner: scanning file 2, record 2700
> > scanner: scanning file 2, record 2800
> > scanner: scanning file 2, record 2900
> > scanner: scanning file 2, record 3000
> > scanner: scanning file 2, record 3100
> > scanner: scanning file 2, record 3200
> > scanner: scanning file 2, record 3300
> > scanner: scanning file 2, record 3400
> > scanner: scanning file 2, record 3500
> > scanner: scanning file 2, record 3600
> > scanner: scanning file 2, record 3700
> > scanner: scanning file 2, record 3800
> > scanner: scanning file 2, record 3900
> > scanner: scanning file 2, record 4000
> > scanner: scanning file 2, record 4100
> > scanner: scanning file 2, record 4200
> > scanner: scanning file 2, record 4300
> > scanner: scanning file 2, record 4400
> > scanner: scanning file 2, record 4500
> > scanner: scanning file 2, record 4600
> > scanner: scanning file 2, record 4700
> > scanner: scanning file 2, record 4800
> > scanner: scanning file 2, record 4900
> > scanner: scanning file 2, record 5000
> > scanner: scanning file 2, record 5100
> > scanner: scanning file 2, record 5200
> > scanner: scanning file 2, record 5300
> > scanner: scanning file 2, record 5400
> > scanner: scanning file 2, record 5500
> > l4f          C:\                 12/13/01  3:45  1 143911040   7624
> > 392891905 E
> > scanner: Opened /dev/rmt/1cbn for read
> > scanner: scanning file 3, record 0
> > scanner: ssid 414985985: found beginning of 4f:SYSTEM STATE:\
> > scanner: scanning file 3, record 100
> > scanner: scanning file 3, record 200
> > scanner: ssid 414990593: found beginning of l4f:SYSTEM STATE:\
> > 4f           SYSTEM STATE:\      12/14/01  3:47  f   8242848     12
> > 414985985 E
> > scanner: ssid 414985985 unexpected end
> > 4f           SYSTEM STATE:\      12/14/01  3:47  f   8242848     12
> > 414985985 E
> > scanner: scanning file 3, record 300
> > scanner: ssid 414996225: found beginning of 4f:C:\
> > scanner: ssid 414985729: found beginning of u4f:/
> > scanner: scanning file 3, record 4
> > ................
> >
> > --
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++++++++++++++++++++++++++++++++++++++++++++++++
Kit Cunningham - idata Limited
Mobile  +64 21 448 444   email: k.cunningham AT idata.co DOT nz
Support Calls to:  0800 backup -         0800 222 587
Support email: support AT idata.co DOT nz
http://www.idata.co.nz
++++++++++++++++++++++++++++++++++++++++++++++++

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