AIT drives

On Fri, 19 Dec 2003 10:40:01 +0000, Bagpuss wrote:

On Fri, 19 Dec 2003 10:30:37 +0000, Rob S
wrote:

On Fri, 19 Dec 2003 00:36:55 -0000, "dorothy.bradbury"
wrote:

-
-DLT is out of the range of SOHO, but AIT isn't such a great substitute.
-VX2 has it's following, but many of the "alternative" tape systems are poor.
-

Interesting debate. We still have several customers who store small databases on
1/4 inch QIC tapes on Tandberg SLR drives. Incredibly reliable.

I've still got an old DEC (as it was at the time) TK tape with VMS on
that worked very recently at least (as backups are only as valid as
the last good read AFAIM concerned).

Er, TK tapes where renamed to DLT when Quantum brought out the
tape division from DEC. You where wondering why some people
favour DLT?

JAB.

--
Jonathan A. Buzzard Email: jonathan (at) buzzard.me.uk
Northumberland, United Kingdom. Tel: +44 1661-832195

On Fri, 19 Dec 2003 18:30:20 +0100, James wrote:

Jonathan Buzzard wrote:
You really need to factor in the cost of tapes. As a DLT IV tape
can be had for £26 brand new with the VAT, and will hold 40GB
native where an AIT1 tape will cost £38 and only hold 35GB native
you can quickly get to DLT being cheaper.

Comparing new drives, it seems the cheapest AIT1 drives are around £470 ex
VAT, the cheapest DLT around £770 ex VAT. If, for the moment, we assume the
sizes are equal (I realise they aren't, but 14% isn't *that* much, and not
every tape would be full), that means that if I save £12/tape with DLT I
have to buy 30 or more tapes to recoup the ~£350 extra I would spend on the
DLT drive. Right now, I don't think I need that many tapes - I'd though
10-12 would be a suitable starting point, 1 per day and a handful over for
last week's/last month's/three months/six months backup...

Perhaps, but then DLT is a realistic archive medium, and all of a sudden
you use more tapes. For example I scanned my brothers wedding photos,
that was 7GB of data (his wedding was in Italy, so he got the negatives
from the photographer). Does not even fit on one DVD, but with DLT
no problem and I still have GB's free for all my other photos. That
is not to mention storing the wav files from ripping CD's for audio
books etc. etc.

It is wildly more reliable,

I'm not trying to be picky, but can you provide a reference for this claim?

Well take a look at the MTBF on the drives taking careful note of
the duty cycles these are for. For DLT the figures are all for
100% duty cycles where for AIT they are for 12.5% duty cycles.
Does that tell you anything?

and has many more sold devices than AIT which might also be a
consideration.

I don't doubt that there's a better second hand market in DLT, but I don't
want to go that route.

Your choice I suppose. Though bare in mind a healthy second hand market
means that if you want to get a tape back in 10 years when the drive
is dead it, you stand a better chance of finding a drive for DLT than
for AIT. There is safety in numbers.

What's it for? If it is for home use have you considered picking up a
DLT 35/70 drive cheap on eBay? There are plenty of drives being sold
of as companies upgrade to SDLT and the like. These drives where
built like bricks so are unlikely to give problems with a little home
use.

I really need a warranty on the drive; I'm just not prepared to go to Ebay -
I've read/experienced too many horror stories.

If you *really* need a warranty then you can afford brand new DLT.

On the other hand there are reliable companies selling DLT with 90 day
warranties on eBay, for example a DLT8000 drive

http://cgi.ebay.co.uk/ws/eBayISAPI.d...tem=2773598380

Pretty competitive with AIT if you ask me. Same company with a 30
day warranty on a DLT7000 drive

http://cgi.ebay.co.uk/ws/eBayISAPI.d...m=277350541 4

Lots cheaper than AIT. I am sure there are plenty of people who would
testify to the reliability of Argents in uk.comp.sys.sun

JAB.

--
Jonathan A. Buzzard Email: jonathan (at) buzzard.me.uk
Northumberland, United Kingdom. Tel: +44 1661-832195

Rob S wrote:

On Fri, 19 Dec 2003 00:36:55 -0000, "dorothy.bradbury"
wrote:

-
-DLT is out of the range of SOHO, but AIT isn't such a great substitute.
-VX2 has it's following, but many of the "alternative" tape systems are poor.
-

Interesting debate. We still have several customers who store small databases on
1/4 inch QIC tapes on Tandberg SLR drives. Incredibly reliable.


Aaaaah - 1/4" tape :-) My mate "the old prof" - (I think his computer
career started when punch cards were a new-fangled thang :-) ) - who's a
pretty hard-boiled low-level tech - reckons the Wangtek 150MB drive was
the most reliable ever :-)

Anyone want any "new" g sealed 1/4" tape media ? I have a few here
that I haven't had the inclination to bin :-) 525's and 1GB I think.

I use a DDS-4 here (for my own private purposes - no critical stuff) and
have found it quite OK - esp as the drive (HP DAT40) cost me £25 at a
computer fair :-) Anyone have opinions on the merits or otherwise of
DDS-4 vs. DDS-3 vs. earlier flavours ? Although it's behaved OK for me
so far, I have to admit that instinct tells me that miniature
helical-scan mech could _so_ easily succumb to a speck of crap/dust ...

Anyone have opinions on the merits or otherwise of
DDS-4 vs. DDS-3 vs. earlier flavours ?

o DDS-4/DDS-3 are improved on than the 2 & 1
---- more reliable, consistent calibration re any-drive-reading

However basic usage criteria matters:
o Clean Defines Error Rate
---- soft-errors & hard-errors mount up in a counter
---- when it gets too high the clean-me LED lights up
o Never miss-handle a cartridge into a drive
---- DAT is not a robust linear tape system
---- DAT is helical scan, high-rpm, high tape handling
---- DAT tape-remove-&-handle-mechanism is fragile

Some general criteria re tape also applies:
o Tape needs time to acclimatise to temperature change
---- it's not a "theoretical risk", it is sound logic
o Storage temperature matters, as does humidity
---- firesafes use water-impregnated gel in cavities, turns to steam
---- media for fire protection needs to be in a media box
---- media for humidity protection needs to be a bag & silica gel

Tape head cleaning was thought by many DAT users to risk
wearing heads out, and consciously/sub-consciously minimised.
Thus they maximised head life, at the expense of backup quality.

Software has at least improved - commonly skimped on in 1993.

For new buyers, it's worth considering a reality:
o In 1993-money a DAT was 550-750ukp
o In 2003-money that 550-750ukp is 1000-1100ukp - DLT level

It still comes down to data-set size.
If your data-set is 20-600MB re home-user, then MO is fine and I
do not agree that tape offers more for the vast jump in cost. For a
business data generally breeds exponentially and whilst DLT costs
more it is the benchmark to judge all others by. I guess people see
laptops & desktops fall in price and believe data drives should too.
As capital opportunity cost of 1993-v-2003 shows, they have really.

A huge number of businesses skimp on backup quality, I recall one
junk accountancy s/w firm with it's DAT tapes stuck in a cardboard
wall unit in direct sunlight and temp change from A/C & doors. The
company was taken over partly because of non-continuing operation
status due to large scale data-loss. Directors got millions, rest 30-days.
IT manager spent more time printing pretty labels & applying them
with a ruler than cleaning the drive (used untrained temps) or storing
the tapes in an environment likely to achieve some in-spec consistency.
Not all companies are so bad, but backups/recovery plan are often poor
and that can FTSE100 companies with one losing 1/3 of their patents
thro failure to re-register due to inaccessible databases. Used a cheap
outsourcing IT contract, screwed up, and cover up over lost future
revenue with the company still counting Goodwill for intell property
whose patents have now lapsed or records actually gone forever.

A lot of people report the later DDS drives (DDS4) are ok, and they
are also DLT users having partly migrated there re cost/capacity or
simply that's what the capex replacement cycle servers came with.
--
Dorothy Bradbury
www.stores.ebay.co.uk/panaflofan for fans, books & other items

On Sat, 20 Dec 2003 00:41:11 +0000, Martin Slaney
wrote:

-Aaaaah - 1/4" tape :-) My mate "the old prof" - (I think his computer
-career started when punch cards were a new-fangled thang :-) ) - who's a
-pretty hard-boiled low-level tech - reckons the Wangtek 150MB drive was
-the most reliable ever :-)

Yep we still have some people using them!
If it ain't broke.....
-
-Anyone want any "new" g sealed 1/4" tape media ? I have a few here
-that I haven't had the inclination to bin :-) 525's and 1GB I think.

I'll take em if you want. Why not put them on ebay? If you do, post me the link!

regards

-Rob
robatwork at mail dot com