Re: DAT Loader failures: secret revealed!

[Chris Hoogendyk]

Daniel Knight wrote:
> 
> >Most guys I know with DAT loaders burn the heads up within a
> >year (your mileage will vary).
> 
> Thanks for your overview. When we used DAT, we had three drives. Each one
> went in at least once a year for warranty service. Once warranty expired,
> it was cheaper to simply replace the drive.
> 
> Since switching to AIT over a year ago, no service has been necessary at
> all.
> 
> Dan Knight, IS manager/webmaster  [EMAIL PROTECTED]
> Baker Book House Company 
> 6030 East Fulton   616-676-9185 x146
> Ada, Michigan 49301 fax 616-676-9573
> 
>   Macs for productivity, Unix for stability, Windows for solitaire
> 

I'll buy that tag line!  ;-)

Actually, I just wanted to toss in my historical 2-cents on DAT drives
(it's been a while).

The overview on DAT, DLT and AIT gave us just that -- an overview of the
type of mechanism. That's useful information to have, but that's like
giving us a comparison of internal combustion cylinder engines versus
turbine engines. If someone throws in their personal experience without
specifying that their car was a Yugo rather than a Toyota, it confuses
the comparison.

During the time I was responsible for daily backups of the Specular
network, I went through a number of DAT drives. I found that the end
manufacturer was critical. This applies to all kinds of drives. The
budget manufacturers may tout that they have the same mechanism, but
they don't talk a lot about their other components. How do they achieve
their budget prices? Well, they use cheaper fans, power supplies, scsi
componentry, etc. The cheap drives were consisently failing after 6 to 9
months. For example, the fan would fail and other components would
overheat and fail. Or the fan was "quiet" ("good PR"), but wasn't
drawing enough air and components ran hotter than they should and failed
sooner than they should.

When I insisted on getting Micronet drives (this was 1995 to 1997), I
had no more problems. Not only did they behave consistently and
flawlessly for approaching two years (that's when Specular was bought
out), but they would read tapes that the other drives failed to read.
The cost of the drives were about double the cheap ones, but they were
rock solid and had top quality compenents throughout.

So, while AIT sounds clearly better than either DAT or DLT, I would bet
that there are significant differences among AIT drives from different
manufacturers even if they have the same core mechanism.

I recently got a new 9.1G IBM drive for my 7100 at home. Since I was
putting it in as an internal drive, that's about all I needed to know.
If I had been getting an external drive, then I would have to worry
about the end manufacturer and all the other components including power,
fan, casing, etc. I didn't feel like worrying, so I tossed the 700MB
internal and just replaced it with the IBM drive.

I suppose I've given more than just 2-cents worth. But then, if you
weren't interested, you wouldn't be arriving here at the last sentance.  ;-)


---

Chris Hoogendyk

-- 
   O__   Network Specialist & Unix Systems Administrator
  c/ /'_ --- Library Information Systems & Technology Services
 (*) \(*) -- W.E.B. Du Bois Library
~~ - University of Massachusetts, Amherst

<[EMAIL PROTECTED]>

---


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Re: DAT Loader failures: secret revealed!

[Daniel Knight]

>Most guys I know with DAT loaders burn the heads up within a
>year (your mileage will vary).

Thanks for your overview. When we used DAT, we had three drives. Each one 
went in at least once a year for warranty service. Once warranty expired, 
it was cheaper to simply replace the drive.

Since switching to AIT over a year ago, no service has been necessary at 
all.

Dan Knight, IS manager/webmaster  [EMAIL PROTECTED]
Baker Book House Company 
6030 East Fulton   616-676-9185 x146
Ada, Michigan 49301 fax 616-676-9573

  Macs for productivity, Unix for stability, Windows for solitaire



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Re: DAT Loader failures: secret revealed!

[matt barkdull]

This is interesting, but I don't think I've ever had a DAT failure 
due to bad heads.  Most of the autoloaders we have have the problem 
with the autoloader itself.  Pull the DAT drive out of the autoloader 
and it works fine most of the time.  We did have one drive go bad, 
but it was related to the "inject" mechanism mis-aligning the tape as 
it fed it in.

Thanks for the info.  Good information.


>Here's why most DATs fail in autoloaders:
>
>Most people buy DAT loaders to compensate for the low capacity per tape.
>The idea is to have the tapes changed automatically in the night or over a
>weekend.  None of us are thrilled with the idea of having to come into the
>office on our personal time to play tape monkey, so this thinking is very
>justified.
>
>What most people do not know is the 4mm mechanism has the lowest head rating
>of 4mm, DLT and 8mm (AIT/M2) technologies (1/5th the head life of AIT).  Now
>that you have a DAT changer automatically handling tape swaps, you're making
>the head unit work longer than it was originally designed to handle.  No DAT
>manufacturer has a special "library" version of their DAT drive with longer
>head ratings.



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DAT Loader failures: secret revealed!

[Stephen Jones]

Here's why most DATs fail in autoloaders:

Most people buy DAT loaders to compensate for the low capacity per tape.
The idea is to have the tapes changed automatically in the night or over a
weekend.  None of us are thrilled with the idea of having to come into the
office on our personal time to play tape monkey, so this thinking is very
justified.

What most people do not know is the 4mm mechanism has the lowest head rating
of 4mm, DLT and 8mm (AIT/M2) technologies (1/5th the head life of AIT).  Now
that you have a DAT changer automatically handling tape swaps, you're making
the head unit work longer than it was originally designed to handle.  No DAT
manufacturer has a special "library" version of their DAT drive with longer
head ratings.

Instead of people using their drives for a couple hours per night, they are
now using them up to 5-10x longer.  End result?  You burn through the heads
'quicker'.  Most guys I know with DAT loaders burn the heads up within a
year (your mileage will vary).  This is like a volkswagon trying to haul a
loaded 18 wheeler rig.  In time, you're going to burn-up the engine or the
tranny.

AIT has 5x the head life of a DAT.  Using the same formula, one would
theoretically get five years of backup before the heads went south for the
winter.  Yet, AIT certainly doesn't have 5x the price tag.  A fifteen tape
library with an AIT-1 drive costs less than $4,250.00 with Retrospect
included.  That's 525GB uncompressed with the higher head rating and
self-cleaning feature.

Here's another newsflash.  AIT-3 is due out next year.  This will drive down
the price of AIT-1 even further.  Because of this, DDS-5 looks like it may
not be released after all.  In other words, eventually, new DDS units will
go the way of the dino.

The above is based on over ten years of personal experience with storage
devices.  I invite all comments via e-mail.

Steve



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