ADSM-L

Re: [ADSM-L] Am I Shoe Shining My LTO4's?

2010-01-29 11:10:56
Subject: Re: [ADSM-L] Am I Shoe Shining My LTO4's?
From: Paul Zarnowski <psz1 AT CORNELL DOT EDU>
To: ADSM-L AT VM.MARIST DOT EDU
Date: Fri, 29 Jan 2010 11:09:21 -0500
As Allen said, find a way to measure the throughput.  We use mrtg for this, 
which gives us some nice graphical long-term history.  We have 8 remote LTO4 
drives, each on it's own 1GE IP connection.  The 8 1GE connections are merged 
onto 1 10GE long-haul network route.  We're using Cisco gear with tape 
acceleration for FCIP and it seems to be working very well.

Details:
Server: P5 570
Tape: IBM 3584, LTO4 drives, with application(TSM)-enabled encryption.
Most of our data is compressed at client
Distance: 200-250 miles

Most of the time, we see performance comparable to local tape.  When we reclaim 
remote tape, we source from local tape (to avoid bogging down network link).  
We do this by marking all of the full remote tapes as "offsite", which forces 
TSM to read input from the local tapes.  This makes the remote library pretty 
much write-only, except when we really need it.

..Paul


At 03:44 PM 1/28/2010, Hart, Charles A wrote:
>We push our 2nd copy over individual FCIP links with write acceleration
>enabled, we use to trunk 6gige links together but ran in to latency
>issues without write acceleration enabled and the technology did not
>allow for write acceleration and trunking so we end up with 3-4 LTO4
>drives down 1gige link with write acceleration.
>
>That said when I run select against the summary table to get timings on
>Backup stgpools the more the more processes we kick off at one the
>slower the speed (makes sense only so much per gige).  (TSM Env AIX p550
>/ IBM LTO4)
>
>LTO4's minimum matching drive speed is 30MBS, so once we push 4
>processes down one link we are pushing less than 30MBS, thereby in
>theory running below the minimum rated drive speed we should be shining
>the drives pretty good.  Does anyone know of a way to validate that
>indeed were shining?
>
>Regards,
>
>Charles
>
>
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--
Paul Zarnowski                            Ph: 607-255-4757
Manager, Storage Services                 Fx: 607-255-8521
719 Rhodes Hall, Ithaca, NY 14853-3801    Em: psz1 AT cornell DOT edu