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[Veritas-bu] DLT Read vs. Write speeds
2002-06-03 14:35:38
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I'm reading a multiplexed backup with the job below. The write jobs you see
are non-multiplexed. Still, that shouldn't make much a difference for
KB/sec like below - NB has to read every block of the MPX tape and cull out
the needed data from there - input speed should be at close to drive speed
of 5-7M/sec or so. The MPX source tape should just mean that the actual
data rate sent to the client would be less that the 409 KB/sec below.
-M
-----Original Message-----
From: Darren Dunham [mailto:ddunham AT taos DOT com]
Sent: Monday, June 03, 2002 12:12 PM
To: Mark.Donaldson AT experianems DOT com
Subject: Re: [Veritas-bu] DLT Read vs. Write speeds
> I've got a DLT7000 library. It seems that read speeds are a tenth of
write
> speeds. Any idea how I can increase the read speed of my tape?
>
>
> r/s w/s kr/s kw/s wait actv wsvc_t asvc_t %w %b device
> 0.0 35.6 0.0 9114.1 0.0 1.0 0.0 27.9 0 99 rmt/1
> 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0 rmt/2
> 0.0 36.6 0.0 9370.1 0.0 1.0 0.0 27.1 0 99 rmt/3
> 1.6 0.0 409.6 0.0 0.0 1.0 0.0 624.8 0 100 rmt/4
>
> ^^^^ ^^^^^
> read write
Depends on what is reading.. Is it the same format as the stuff that
was written (netbackup?)
Can you read any faster with 'dd' rather than netbackup?
'dd if=/dev/rmt/4cbn of=/dev/null bs=64k'?
--
Darren Dunham ddunham AT taos DOT com
Unix System Administrator Taos - The SysAdmin Company
Got some Dr Pepper? San Francisco, CA bay area
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<TITLE>RE: [Veritas-bu] DLT Read vs. Write speeds</TITLE>
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<P><FONT SIZE=3D2>I'm reading a multiplexed backup with the job =
below. The write jobs you see are non-multiplexed. Still, =
that shouldn't make much a difference for KB/sec like below - NB has to =
read every block of the MPX tape and cull out the needed data from =
there - input speed should be at close to drive speed of 5-7M/sec or =
so. The MPX source tape should just mean that the actual data =
rate sent to the client would be less that the 409 KB/sec =
below.</FONT></P>
<P><FONT SIZE=3D2>-M</FONT>
</P>
<P><FONT SIZE=3D2>-----Original Message-----</FONT>
<BR><FONT SIZE=3D2>From: Darren Dunham [<A =
HREF=3D"mailto:ddunham AT taos DOT com">mailto:ddunham AT taos DOT
com</A>]</FONT>
<BR><FONT SIZE=3D2>Sent: Monday, June 03, 2002 12:12 PM</FONT>
<BR><FONT SIZE=3D2>To: Mark.Donaldson AT experianems DOT com</FONT>
<BR><FONT SIZE=3D2>Subject: Re: [Veritas-bu] DLT Read vs. Write =
speeds</FONT>
</P>
<BR>
<P><FONT SIZE=3D2>> I've got a DLT7000 library. It seems that =
read speeds are a tenth of write</FONT>
<BR><FONT SIZE=3D2>> speeds. Any idea how I can increase the =
read speed of my tape?</FONT>
<BR><FONT SIZE=3D2>> </FONT>
<BR><FONT SIZE=3D2>> </FONT>
<BR><FONT SIZE=3D2>> r/s w/s =
kr/s kw/s wait actv wsvc_t asvc_t %w %b =
device</FONT>
<BR><FONT SIZE=3D2>> 0.0 35.6 0.0 =
9114.1 0.0 1.0 0.0 =
27.9 0 99 rmt/1</FONT>
<BR><FONT SIZE=3D2>> 0.0 0.0 =
0.0 0.0 0.0 0.0 =
0.0 0.0 0 0 rmt/2</FONT>
<BR><FONT SIZE=3D2>> 0.0 36.6 0.0 =
9370.1 0.0 1.0 0.0 =
27.1 0 99 rmt/3</FONT>
<BR><FONT SIZE=3D2>> 1.6 0.0 =
409.6 0.0 0.0 1.0 =
0.0 624.8 0 100 rmt/4</FONT>
<BR><FONT SIZE=3D2>> </FONT>
<BR><FONT =
SIZE=3D2>>  =
; ^^^^ ^^^^^</FONT>
<BR><FONT =
SIZE=3D2>>  =
; read write</FONT>
</P>
<P><FONT SIZE=3D2>Depends on what is reading.. Is it the same =
format as the stuff that</FONT>
<BR><FONT SIZE=3D2>was written (netbackup?)</FONT>
</P>
<P><FONT SIZE=3D2>Can you read any faster with 'dd' rather than =
netbackup?</FONT>
<BR><FONT SIZE=3D2>'dd if=3D/dev/rmt/4cbn of=3D/dev/null =
bs=3D64k'?</FONT>
</P>
<P><FONT SIZE=3D2>-- </FONT>
<BR><FONT SIZE=3D2>Darren =
Dunham =
=
=
ddunham AT taos DOT com</FONT>
<BR><FONT SIZE=3D2>Unix System =
Administrator  =
; Taos - The =
SysAdmin Company</FONT>
<BR><FONT SIZE=3D2>Got some Dr =
Pepper?  =
;  =
; San Francisco, CA bay area</FONT>
<BR><FONT SIZE=3D2> =
< This line left intentionally blank to confuse you. ></FONT>
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