ADSM-L

Re: FW: Tape Drive Choices: What, and why?

2006-08-08 16:48:44
Subject: Re: FW: Tape Drive Choices: What, and why?
From: Zoltan Forray/AC/VCU <zforray AT VCU DOT EDU>
To: ADSM-L AT VM.MARIST DOT EDU
Date: Tue, 8 Aug 2006 16:45:05 -0400
You won't get that sentiment from me.

As I have said in the past, my experience with LTO2 and 3583 library is
that they are !@#$%^&* garbage.  Even IBM stated that LTO was never
designed to handle the load we are putting through them (we have over 400
tapes in use per 3583-L72 library).   Every drive we purchased has been
replaced AT LEAST twice, in the past 1.5-years we have had LTO
drives/libraries.  The libraries need to be "power cycled" at least once a
week, sometimes more (absolutely every piece of firmware/software between
the AIX systems and the libraries themselves, have been updated to the
latest available - no it's not power - everything is on
UPS/battery/conditioned).

This is why we are moving to 3592-E05 drives.  Besides the capacity
difference, the reliability we have seen with 3590 drives (even those that
are 10+ years old), far exceeds the LTO's.  We mount 1000's of 3590 tapes,
daily.  If we have 1-failure in 2-3 weeks, that is rare.

Granted the 3592-E05 drives are new and "disposable/FRU" technology vs.
field-repairable, so time will tell.




"Allen S. Rout" <asr AT UFL DOT EDU>
Sent by: "ADSM: Dist Stor Manager" <ADSM-L AT VM.MARIST DOT EDU>
08/08/2006 02:08 PM
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Re: [ADSM-L] FW: Tape Drive Choices: What, and why?






>> On Tue, 8 Aug 2006 11:37:37 -0400, Paul Zarnowski <psz1 AT CORNELL DOT EDU>
said:

> This was more true with LTO-1 than with -2 or -3.  The later
> generation drives can vary their speed to try to match the data rate,
> thus avoiding some backhitching.  But Tom is correct that the motors
> in the 3592 drives are probably bigger and more powerful, and can
> thus backhitch more quickly.  (this is my guess, not fact)


If I recall correctly, the superior 3592 backhitch was related to a
special track ("servo track"?) which permitted precise high-speed
positioning.  This also aids general purpose seek behavior. The
varying speeds would certainly help.

The basic summary of the responses I've gotten offline is that LTO is
doing much better than it had initially; it seems that the current
3592s still have an edge, but not nearly so broad as was the case.

Most interestingly, I didn't see any particular discussion about any
tech _other_ than LTO or 3592, apart from one "Pulled back a bloody
stump" story about helical-scan.

This meshes neatly with a campus-level query I sent out a few weeks
back; to my surprise, LTO utterly dominated that list of tape techs,
too. Discussion of other tech lines was all in the past tense.  It
appears that the LTO alliance has kicked tush and taken names.  Rawk
On.


- Allen S. Rout

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