On Monday, November 22, 2010 12:49:01 pm Stefan G. Weichinger did opine:
At first: Gene you seem to have used a different email-adress so your
reply didn't make it to the list.
Sorry bout that, I should change my sub, I'm getting tired of gmails
automatic nuking of my own posts.
I just quote it here:
Am 22.11.2010 12:09, schrieb gene heskett:
I gave up on the use of an earlier dat machine after wearing out half
a dozen of them. Life of the rotating head seems to be not much over
1000 hours, and while I am capable of replacing the heads myself, no
one would sell me the replacement head, claiming it took all sorts of
fancy machinery to do it right. So I wound up sending a $400 drive
to Oklahoma City every thanksgiving week, getting it back for about
$350 COD sometime after Christmas. Eventually I bought a big hard
drive and switched to virtual tapes, which have turned out to be many
times faster _AND_ far more dependable. Replaced once with no data
loss after smartd complained, the replacement is a full terrabyte and
spinning flawlessly 24/7. For me, the relatively much lower cost and
the dependability are a huge plus. Throw in that a recovery can be
done from that hard drive in 5 to 10% of the time it would take from
purely sequential tapes, and the choice is an absolute no brainer. I
have spent less than 20% of the money for hard drives that I would
have spent on dat drives and tapes in the nominally 5 years since I
switched.
For those that need off-site secure storage, just rotate the drive out
for another identically prepared one at the end of say every other
dumpcycle. Or, better yet IMNSHO, just ssh copy it over the net to
the off-site location, reducing the drives exposure to the knocks &
bumps of the real world. I have considered adding another drive to a
machine that runs my cnc milling machine just for that, on site, but
in another building, also on a huge ups, but the PATA interface on
that particular motherboard doesn't handle 2 drives per cable
properly. For running the milling machine, its not broke.
But that demo's how one might think about 'off-site' and its all
behind a router/NAT on the local, much more secure address block.
As for the head drum replacement scene, I have replaced around $80k or
more in dvc-pro broadcast videotape machines, they are about 1/5th
the size of a dat head drum, priced originally at $1500 ea, life 7 to
10k hours. I am a retired tv CE, and a C.E.T.
That, and a $1.33 will get you a big cuppa joe at 7-11.
Advice is worth 2 cents, maybe.
More than 2, for sure
Your hints regarding the rotating head sound good to me ... and it also
matches my experience with those devices.
Harddisk-based backups are no option there,
And why not, they are big enough for the job these days?
so I rather consider buying
an LTO drive as I think (and read and google) that those drives and the
used technology are more reliable ...
I can't argue with anything but the cost, of both the drives and the media,
something I can't begin to justify on my income as a retiree. However,
since the hard drive head flies on an air cushion, the wear rate when
spinning 24/7 is un-measureable, so only the start stop counts and the
spindle are the immediate factors barring particulate contamination of the
drive housing. Unless some new air injection technique to float the tape as
it passes over the heads in a tape drive has been developed, then the tape
still runs in close contact with the read/write head(s) and there will be a
wear factor involved. But I have NDI how the LTO drives approach and or
treat that problem.
The then legendary Ampex 600 audio tape machine from 50+ years ago solved
it by making their heads with gaps 30 thousandths deep, and figured on a
mils wear per thousand hours of tape motion. So they, with a recalibration
of the recording bias used at about 1000 hour intervals, could maintain
their performance for extended periods of time. Perhaps the LTO's are
using a similar idea, but with modern micro-controllers, are doing on a per
tape basis what it took me an hour or more to do in 1957? My best SWAG
anyway.
I have an LTO2 here and some others (up to LTO4) at customers, good
performance so far.
Thanks, Stefan
--
Cheers, Gene
"There are four boxes to be used in defense of liberty:
soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Another megabytes the dust.
