[Info-vax] TLZ7

[AEF]

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