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Thanks for you timely response Jeff.
Cecil
-----Original Message-----
From: Jeff Bryer [mailto:bryer AT sfu DOT ca]
Sent: Sunday, August 17, 2003 7:48 PM
To: veritas-bu AT mailman.eng.auburn DOT edu
Subject: [Veritas-bu] Re: Backup dilemma
>I have to do a weekly full backup of a system that has 17 partitions and
>about 500 GB of data. The backup will be done on the weekend, when there
are
>few other jobs running. Here are some specs:
>network: 100 MB/sec (12.5 MB/sec)
>SCSI-2 connection : (40 MB/sec)80 MB/sec (two drives)
>Drives: 2 SDLT220's 79.2 GB/hr
>Produce: Netbackup Datacenter 4.5
You also have to take in to consideration the system that houses this data,
and the makeup of the data (it it compressible, few big files vs lots of
little files).
If you have 500GB of data and a 12 hour window, then assuming no compression
one SDLT220 will not back up that amount of data in that window. So you'll
need to use both drives, and feed them each at 11MB/s (to eliminate
shoe-shining)
assuming no compression which means your network must handle 22MB/s. It
also
assumes your system can push the data out at 22MB/s as you say you only
have one system to back up.
If your data is compressible, then you can use one drive and keep it fed
at 11-22MB/s (depending on how compressible). If you want to use both
drives,
and assuming 2:1 compression you'll need to fed them at 44MB/s.
As has been suggested, you can go to GigE (on the both the client and the
server)
and that will shift the bottleneck away from the network. Then you have to
ensure
that your system can push the data out fast enough to keep the drives
streaming.
Mutliplexing is intended to aggregate the network feeds into one to keep the
drive
streaming. Unfortunately you only have one system to back up. If you find
that your
system is able to push out two streams (one to each tape drive) fast enough
to
keep the drives streaming you won't need multiplexing. If you find that
your system
pushes a stream out at 7.5MB/s and you can add a second stream at 7.5MB/s
(but you can't
get one stream at 15MB/s) then you'll want to try multiplexing (we have a
Novell
system like this).
--
Jeff Bryer bryer AT sfu DOT ca
Systems Administrator (604) 291-4935
Academic Computing, Simon Fraser University
_______________________________________________
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] Re: Backup dilemma</TITLE>
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<P><FONT SIZE=3D2>Thanks for you timely response Jeff.</FONT>
<BR><FONT SIZE=3D2>Cecil</FONT>
</P>
<P><FONT SIZE=3D2>-----Original Message-----</FONT>
<BR><FONT SIZE=3D2>From: Jeff Bryer [<A =
HREF=3D"mailto:bryer AT sfu DOT ca">mailto:bryer AT sfu DOT ca</A>] </FONT>
<BR><FONT SIZE=3D2>Sent: Sunday, August 17, 2003 7:48 PM</FONT>
<BR><FONT SIZE=3D2>To: veritas-bu AT mailman.eng.auburn DOT edu</FONT>
<BR><FONT SIZE=3D2>Subject: [Veritas-bu] Re: Backup dilemma</FONT>
</P>
<P><FONT SIZE=3D2>>I have to do a weekly full backup of a system =
that has 17 partitions and</FONT>
<BR><FONT SIZE=3D2>>about 500 GB of data. The backup will be done on =
the weekend, when there are</FONT>
<BR><FONT SIZE=3D2>>few other jobs running. Here are some =
specs:</FONT>
<BR><FONT SIZE=3D2>>network: 100 MB/sec (12.5 MB/sec)</FONT>
<BR><FONT SIZE=3D2>>SCSI-2 connection : (40 MB/sec)80 MB/sec (two =
drives)</FONT>
<BR><FONT SIZE=3D2>>Drives: 2 SDLT220's 79.2 GB/hr</FONT>
<BR><FONT SIZE=3D2>>Produce: Netbackup Datacenter 4.5</FONT>
</P>
<P><FONT SIZE=3D2>You also have to take in to consideration the system =
that houses this data,</FONT>
<BR><FONT SIZE=3D2>and the makeup of the data (it it compressible, few =
big files vs lots of little files).</FONT>
</P>
<P><FONT SIZE=3D2>If you have 500GB of data and a 12 hour window, then =
assuming no compression </FONT>
<BR><FONT SIZE=3D2>one SDLT220 will not back up that amount of data in =
that window. So you'll</FONT>
<BR><FONT SIZE=3D2>need to use both drives, and feed them each at =
11MB/s (to eliminate shoe-shining)</FONT>
<BR><FONT SIZE=3D2>assuming no compression which means your network =
must handle 22MB/s. It also</FONT>
<BR><FONT SIZE=3D2>assumes your system can push the data out at 22MB/s =
as you say you only </FONT>
<BR><FONT SIZE=3D2>have one system to back up.</FONT>
</P>
<P><FONT SIZE=3D2>If your data is compressible, then you can use one =
drive and keep it fed</FONT>
<BR><FONT SIZE=3D2>at 11-22MB/s (depending on how compressible). =
If you want to use both drives,</FONT>
<BR><FONT SIZE=3D2>and assuming 2:1 compression you'll need to fed them =
at 44MB/s.</FONT>
</P>
<P><FONT SIZE=3D2>As has been suggested, you can go to GigE (on the =
both the client and the server)</FONT>
<BR><FONT SIZE=3D2>and that will shift the bottleneck away from the =
network. Then you have to ensure</FONT>
<BR><FONT SIZE=3D2>that your system can push the data out fast enough =
to keep the drives streaming.</FONT>
</P>
<P><FONT SIZE=3D2>Mutliplexing is intended to aggregate the network =
feeds into one to keep the drive</FONT>
<BR><FONT SIZE=3D2>streaming. Unfortunately you only have one =
system to back up. If you find that your </FONT>
<BR><FONT SIZE=3D2>system is able to push out two streams (one to each =
tape drive) fast enough to</FONT>
<BR><FONT SIZE=3D2>keep the drives streaming you won't need =
multiplexing. If you find that your system</FONT>
<BR><FONT SIZE=3D2>pushes a stream out at 7.5MB/s and you can add a =
second stream at 7.5MB/s (but you can't</FONT>
<BR><FONT SIZE=3D2>get one stream at 15MB/s) then you'll want to try =
multiplexing (we have a Novell</FONT>
<BR><FONT SIZE=3D2>system like this).</FONT>
</P>
<BR>
<P><FONT SIZE=3D2>-- </FONT>
<BR><FONT SIZE=3D2>Jeff Bryer =
=
=
bryer AT sfu DOT ca</FONT>
<BR><FONT SIZE=3D2>Systems Administrator =
=
(604) 291-4935</FONT>
<BR><FONT SIZE=3D2>Academic Computing, Simon Fraser University</FONT>
<BR><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>
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