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I had significant problems in image duplication from multiplexed tapes. The
problem shows up when you're trying to duplicate a single image from a
larger set of images. NB has to sort that image from the other information
that's not to be duplicated.
So for every 10 MByte read, I wrote a single MByte. It was very inefficient
and took forever. I eventually broke my backups into two sets, those that
get duplicated and those that don't. The ones that get duplicated are
demux'd so at dup time I write everything I read. I can duplicate very
quickly now.
If you duplicate from mux'd images & you're doing the whole set, you should
probably look at the "-mpx" flag on bpduplicate.
-M
-mpx Specifies that when duplicating multiplexed backups,
NetBackup will create multiplexed backups on the destination
media. This reduces the time to duplicate multiplexed
backups.
Multiplexed duplication is not supported for:
- Non-multiplexed backups
- Backups from disk type storage units
- Backups to disk type storage units
- Auspex-FastBackup, FlashBackup, or NDMP backups
If backups in the above categories are encountered during
duplication, NetBackup duplicates them first and uses non-
multiplexed duplication. Then, the multiplexed backups are
duplicated by using multiplexed duplication.
If all the backups in a multiplexed group are not
duplicated, the duplicated multiplexed group will have a
different layout of fragments. (A multiplexed group is a set
of backups that were multiplexed together during a single
multiplexing session.)
If this option is not specified, all backups are duplicated
using non-multiplexed duplication.
For more information on multiplexing, see your NetBackup
system administrator's guide.
-----Original Message-----
From: Brian Chase [mailto:vaxzilla AT jarai DOT org]
Sent: Monday, January 27, 2003 11:39 AM
To: Kennedy, Jeffrey
Cc: Deb; Zink, Melanie; veritas-bu AT mailman.eng.auburn DOT edu
Subject: RE: [Veritas-bu] Considering moving to NetBackup
On Mon, 27 Jan 2003, Kennedy, Jeffrey wrote:
> Slow as in sloooooooowwwww. When I tried vaulting from tape to tape
> with original backups using a 6 MPX, I was seeing kb/sec transfer rate.
> No matter what I did, or Veritas tech support had me try, I got a
> maximum transfer rate of 700kb/sec. Not really feasible in today's data
> center.
>
> But that could have just been me. Tech support seemed stumped.
When using MPX, you're splitting the stream across multiple drives.
Did you have multiple drives available (and occupied) by the MPX'ed
tapes that were being copied to the non-MPX offsite?
I'd imagine that if you had, say, only one drive available on the
"read" end of that copy, the library would be spending an awful lot of
time changing between tapes, seeking, and rewinding. That scenerio
could certainly explain seeing such low throughput.
-brian.
_______________________________________________
Veritas-bu maillist - Veritas-bu AT mailman.eng.auburn DOT edu
http://mailman.eng.auburn.edu/mailman/listinfo/veritas-bu
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<TITLE>RE: [Veritas-bu] Considering moving to NetBackup</TITLE>
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<P><FONT SIZE=3D2>I had significant problems in image duplication from =
multiplexed tapes. The problem shows up when you're trying to =
duplicate a single image from a larger set of images. NB has to =
sort that image from the other information that's not to be =
duplicated.</FONT></P>
<P><FONT SIZE=3D2>So for every 10 MByte read, I wrote a single =
MByte. It was very inefficient and took forever. I =
eventually broke my backups into two sets, those that get duplicated =
and those that don't. The ones that get duplicated are demux'd so =
at dup time I write everything I read. I can duplicate very =
quickly now.</FONT></P>
<P><FONT SIZE=3D2>If you duplicate from mux'd images & you're doing =
the whole set, you should probably look at the "-mpx" flag on =
bpduplicate.</FONT></P>
<P><FONT SIZE=3D2>-M</FONT>
</P>
<P><FONT SIZE=3D2> =
-mpx Specifies that when duplicating =
multiplexed backups,</FONT>
<BR><FONT =
SIZE=3D2> &nb=
sp; NetBackup will create multiplexed backups =
on the destination</FONT>
<BR><FONT =
SIZE=3D2> &nb=
sp; media. This reduces the time to duplicate =
multiplexed</FONT>
<BR><FONT =
SIZE=3D2> &nb=
sp; backups.</FONT>
</P>
<P><FONT =
SIZE=3D2> &nb=
sp; Multiplexed duplication is not supported =
for:</FONT>
</P>
<P><FONT =
SIZE=3D2> &nb=
sp; - Non-multiplexed backups</FONT>
<BR><FONT =
SIZE=3D2> &nb=
sp; - Backups from disk type storage =
units</FONT>
<BR><FONT =
SIZE=3D2> &nb=
sp; - Backups to disk type storage units</FONT>
<BR><FONT =
SIZE=3D2> &nb=
sp; - Auspex-FastBackup, FlashBackup, or NDMP =
backups</FONT>
</P>
<P><FONT =
SIZE=3D2> &nb=
sp; If backups in the above categories are =
encountered during</FONT>
<BR><FONT =
SIZE=3D2> &nb=
sp; duplication, NetBackup duplicates them =
first and uses non-</FONT>
<BR><FONT =
SIZE=3D2> &nb=
sp; multiplexed duplication. Then, the =
multiplexed backups are</FONT>
<BR><FONT =
SIZE=3D2> &nb=
sp; duplicated by using multiplexed =
duplication.</FONT>
</P>
<P><FONT =
SIZE=3D2> &nb=
sp; If all the backups in a multiplexed group =
are not</FONT>
<BR><FONT =
SIZE=3D2> &nb=
sp; duplicated, the duplicated multiplexed =
group will have a</FONT>
<BR><FONT =
SIZE=3D2> &nb=
sp; different layout of fragments. (A =
multiplexed group is a set</FONT>
<BR><FONT =
SIZE=3D2> &nb=
sp; of backups that were multiplexed together =
during a single</FONT>
<BR><FONT =
SIZE=3D2> &nb=
sp; multiplexing session.)</FONT>
</P>
<P><FONT =
SIZE=3D2> &nb=
sp; If this option is not specified, all =
backups are duplicated</FONT>
<BR><FONT =
SIZE=3D2> &nb=
sp; using non-multiplexed duplication.</FONT>
</P>
<P><FONT =
SIZE=3D2> &nb=
sp; For more information on multiplexing, see =
your NetBackup</FONT>
<BR><FONT =
SIZE=3D2> &nb=
sp; system administrator's guide.</FONT>
</P>
<P><FONT SIZE=3D2>-----Original Message-----</FONT>
<BR><FONT SIZE=3D2>From: Brian Chase [<A =
HREF=3D"mailto:vaxzilla AT jarai DOT org">mailto:vaxzilla AT jarai DOT
org</A>]</FONT>=
<BR><FONT SIZE=3D2>Sent: Monday, January 27, 2003 11:39 AM</FONT>
<BR><FONT SIZE=3D2>To: Kennedy, Jeffrey</FONT>
<BR><FONT SIZE=3D2>Cc: Deb; Zink, Melanie; =
veritas-bu AT mailman.eng.auburn DOT edu</FONT>
<BR><FONT SIZE=3D2>Subject: RE: [Veritas-bu] Considering moving to =
NetBackup</FONT>
</P>
<BR>
<P><FONT SIZE=3D2>On Mon, 27 Jan 2003, Kennedy, Jeffrey wrote:</FONT>
</P>
<P><FONT SIZE=3D2>> Slow as in sloooooooowwwww. When I tried =
vaulting from tape to tape</FONT>
<BR><FONT SIZE=3D2>> with original backups using a 6 MPX, I was =
seeing kb/sec transfer rate.</FONT>
<BR><FONT SIZE=3D2>> No matter what I did, or Veritas tech support =
had me try, I got a</FONT>
<BR><FONT SIZE=3D2>> maximum transfer rate of 700kb/sec. Not =
really feasible in today's data</FONT>
<BR><FONT SIZE=3D2>> center.</FONT>
<BR><FONT SIZE=3D2>></FONT>
<BR><FONT SIZE=3D2>> But that could have just been me. Tech =
support seemed stumped.</FONT>
</P>
<P><FONT SIZE=3D2>When using MPX, you're splitting the stream across =
multiple drives.</FONT>
<BR><FONT SIZE=3D2>Did you have multiple drives available (and =
occupied) by the MPX'ed</FONT>
<BR><FONT SIZE=3D2>tapes that were being copied to the non-MPX =
offsite?</FONT>
</P>
<P><FONT SIZE=3D2>I'd imagine that if you had, say, only one drive =
available on the</FONT>
<BR><FONT SIZE=3D2>"read" end of that copy, the library would =
be spending an awful lot of</FONT>
<BR><FONT SIZE=3D2>time changing between tapes, seeking, and =
rewinding. That scenerio</FONT>
<BR><FONT SIZE=3D2>could certainly explain seeing such low =
throughput.</FONT>
</P>
<P><FONT SIZE=3D2>-brian.</FONT>
</P>
<P><FONT =
SIZE=3D2>_______________________________________________</FONT>
<BR><FONT SIZE=3D2>Veritas-bu maillist - =
Veritas-bu AT mailman.eng.auburn DOT edu</FONT>
<BR><FONT SIZE=3D2><A =
HREF=3D"http://mailman.eng.auburn.edu/mailman/listinfo/veritas-bu"; =
TARGET=3D"_blank">http://mailman.eng.auburn.edu/mailman/listinfo/veritas=
-bu</A></FONT>
</P>
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