[Info-vax] TLZ7

[Mike Rechtman]

On 08/11/10 13:53, AEF wrote:
> On Nov 7, 7:06 pm, John Wallace<johnwalla... at yahoo.co.uk>  wrote:
>> On Nov 6, 9:38 am, Kari Uusimäki
>>
>>
>>
>> <uusim... at exdecWITHOUTTHISfinland.org>  wrote:
>>> On 5.11.2010 2:06, Alan Frisbie wrote:
>>
>>>> On 11/4/2010 3:40 PM, Kari Uusim ki wrote:
>>
>>>>> DLT, SDLT or LTO tape drives are very reliable and have much better
>>>>> performance and therefore they are mostly used in production
>>>>> environments.
>>
>>>> In general I would agree with you, but I have experienced a
>>>> tape failure rate (with new tapes) between ten and twenty percent.
>>
>>>> Once they have been successfully used, they seem to stay good for
>>>> many more uses, but I never trust new tapes. This applies to
>>>> both SDLT-1 160/320GB and SDLT-2 300/600GB tapes. Just last
>>>> month I bought ten of each, and two in each batch were bad
>>>> (parity / CRC errors).
>>
>>>> With DAT tapes, they generally failed with crinkled tape
>>>> hanging out of the cartridge, but I didn't have much of a
>>>> problem with parity errors as long as I regularly used the
>>>> cleaning tape.
>>
>>>> Alan "The other AEF" Frisbie
>>
>>> I do agree about the bad tape quality. I've also seen tape failure with
>>> the newest tape types (SDLT and LTO). I haven't investigated the reason
>>> to the failures, but because most tapes stay good for years of
>>> continuous use I suspect the quality is varying. Especially because the
>>> failure rate of new tapes is high.
>>> Of course the new tape types with extremely high density and
>>> microscopous particles are more sensitive to dust and other contaminats
>>> than older tape types.
>>
>>> The complex mechanical design of the DAT (and the AIT) tape drive causes
>>> the tape to wear more than with the more straightforward designs (DLT,
>>> SDLT, LTO). The amount of moving parts in the DAT mechanism also causes
>>> failures.
>>
>>> Btw I haven't seen a single mechanical failure (breakdown) of a DLT
>>> drive (or the predecessors; TK50 and TK70) during the 20 years I've been
>>> in this business. The parts wearing out are the take-up leader and the
>>> read-write head, but the construction is otherwise so sturdy that it
>>> surely is capable of running hundreds of thousands hours.
>>
>>> Kari
>>
>> In my experience quite a few TK50s and TK70s failed due to less than
>> ideal user interface design (specifically for tape unload), but once
>> the users were educated not to attempt to raise the handle till the
>> drive was in the right state, DLT drives were far more reliable than
>> DAT.
>
> Same here: I haven't had *any* trouble with my TZ88 (but I am the only
> user, and I know to wait for the green light before lifting the
> handle!).
>
> And using DDS-1 saved the day with the TLZ07s.
>
> Oh, there was one exception: One TLZ07 (or 09? I'll check next chance
> I get) drive makes tapes no other drive can read, and no other drive
> can make tapes that this drive can read! It's like a new "species
> offshoot".
>
> AEF

Do DAT drives have the possibility of heads being out of adjustment? 'Cause 
thats what it sounds like.
-- 
Mike R.
Home: http://alpha.mike-r.com/
QOTD: http://alpha.mike-r.com/php/qotd.php
No Micro$oft products were used in the URLs above, or in preparing this message.
Recommended reading: http://www.catb.org/~esr/faqs/smart-questions.html#before