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two comments here...
1.) I don't think you'll see much of a difference in restoring a single or
small number of files when using a high MPX setting, but for 100s of files
or an entire system, you should see a difference (in theory). If you have
some other bottleneck, though, like the disk you're writing to or the
network speed, pulling from the tape faster or slower isn't going to be
noticable. In fact, if you have a bottleneck somewhere else, using MPX
and having the data spread across more of the tape (essentially reading it
slower) may actually keep the drive from rewinding a lot during the
restore, which could actually help performance.
2.) if you're taking a special backup for testing during the day, from an
unused media server or with a short retention that doesn't get used on any
other active jobs, even though you have a high MPX value set, it's not
going to be able to MPX with anything else and it's going to be the same
as having MPX at 1.
- Scott
"Mark T Wragge" <storage AT ttt DOT ie>
Sent by: veritas-bu-admin AT mailman.eng.auburn DOT edu
09/19/2003 08:23 AM
Please respond to "Mark T Wragge"
To: <veritas-bu AT mailman.eng.auburn DOT edu>
cc:
Subject: [Veritas-bu] will multiplexing effect restore time
I have often been told that the level of multiplexing will effect the
restore time of a client. We are running multiplexing of between 6 to 8
jobs at a time. i would expect the restore time to be slower with this
level of multiplexing than a restore where the multiplexing was set to
one. An engineer has run some tests and reported that there is not much
difference in restore times between the multiplexed and non-multiplexed
backups.
We are a Windows 2000 environment with LTO tape technology.
Regards, Mark
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<br><font size=2 face="Arial">two comments here...</font>
<br>
<br><font size=2 face="Arial">1.) I don't think you'll see much of a difference
in restoring a single or small number of files when using a high MPX setting,
but for 100s of files or an entire system, you should see a difference (in
theory). If you have some other bottleneck, though, like the disk you're
writing to or the network speed, pulling from the tape faster or slower isn't
going to be noticable. In fact, if you have a bottleneck somewhere else,
using MPX and having the data spread across more of the tape (essentially
reading it slower) may actually keep the drive from rewinding a lot during the
restore, which could actually help performance.</font>
<br>
<br><font size=2 face="Arial">2.) if you're taking a special backup for testing
during the day, from an unused media server or with a short retention that
doesn't get used on any other active jobs, even though you have a high MPX
value set, it's not going to be able to MPX with anything else and it's going
to be the same as having MPX at 1.</font>
<br>
<br>
<br><font size=2 face="Arial">- Scott</font>
<br>
<br>
<br>
<br>
<table width=100%>
<tr valign=top>
<td>
<td><font size=1 face="sans-serif"><b>"Mark T Wragge" <storage AT
ttt DOT ie></b></font>
<br><font size=1 face="sans-serif">Sent by: veritas-bu-admin AT
mailman.eng.auburn DOT edu</font>
<p><font size=1 face="sans-serif">09/19/2003 08:23 AM</font>
<br><font size=1 face="sans-serif">Please respond to "Mark T
Wragge"</font>
<br>
<td><font size=1 face="Arial"> </font>
<br><font size=1 face="sans-serif"> To:
<veritas-bu AT mailman.eng.auburn DOT edu></font>
<br><font size=1 face="sans-serif"> cc:
</font>
<br><font size=1 face="sans-serif"> Subject:
[Veritas-bu] will multiplexing effect restore
time</font></table>
<br>
<br>
<br><font size=2 face="Arial">I have often been told that the level of
multiplexing will effect the restore time of a client. We are running
multiplexing of between 6 to 8 jobs at a time. i would expect the restore
time to be slower with this level of multiplexing than a restore where the
multiplexing was set to one. An engineer has run some tests and reported
that there is not much difference in restore times between the multiplexed and
non-multiplexed backups.</font>
<br><font size=3 face="Times New Roman"> </font>
<br><font size=2 face="Arial">We are a Windows 2000 environment with LTO tape
technology.</font>
<br><font size=3 face="Times New Roman"> </font>
<br><font size=2 face="Arial">Regards, Mark</font>
<br>
<br>
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