ADSM-L

Re: [ADSM-L] measuring shoeshining ?

2007-04-17 01:09:45
Subject: Re: [ADSM-L] measuring shoeshining ?
From: Roger Deschner <rogerd AT UIC DOT EDU>
To: ADSM-L AT VM.MARIST DOT EDU
Date: Tue, 17 Apr 2007 00:09:20 -0500
Interesting question. I would simply measure tape throughput. A question
is, where to get tape throguhput stats. You could scan the activity log
for migration and reclamation completed stats, and also look for backup
sessions that mounted a tape and grab their accounting stats.

Is anybody from someplace like Quantum or the LTO consortium listening?
I wonder if the tape drives many of us use (LTO and SDLT) collect any of
this information. In the old days, you could watch and listen to tape
drives, and a drive that was shoeshining made a distinctive "wheeee,
wheeee, wheeee" sound, whereas one that was effectively streaming made
more of a motorized, productive, grrurrurrurr. Now they're imprisoned in
libraries and you can't even see the blinking lights anymore, much less
listen to them. Hmmm, This gives me an idea - on our ATL/Quantum tape
libraries, you can open a door on the back and have access to the back
of the tape drives. I should borrow a doctor's stethescope and see if I
can hear anything from the back.

Roger Deschner      University of Illinois at Chicago     rogerd AT uic DOT edu


On Tue, 17 Apr 2007, Peter Billam wrote:

>
>> when the client is too slow to keep the tape drive streaming, the tape
>> stops and starts - shoeshining. This really wears out your tapes. They
>> say that DLT and LTO tapes are good for some huge number of passes in
>> the millions, but once you start shoeshining you can reach those numbers
>> real quick.
>> ...
>> The only way to positively prevent shoeshining is to buy more disks,
>> and insure that all tape writing is done via TSM Migration from local
>> server disk.
>
>Is there a good way of collecting daily shoeshining statistics ?
>
>Regards, Peter
>
>AUS/TAS/DPIW/CIT/Servers hbt/lnd/l8   6233 3061   http://www.pjb.com.au
>Pasari, pasarimos    dice el agua    y canta la verdad contra la piedra
> -- Pablo Neruda
>

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