8 mm tapes

Dave McGuire mcguire at neurotica.com
Fri Sep 24 08:43:55 CDT 2010


On 9/23/10 10:52 AM, jim s wrote:
>> <snip>
>> "Write-only media", yes. I've never seen a tape as unreliable as an
>> 8200/8500.
>
> I have tapes that are 20 years old. All are readable. The error rate is
> lower than with 1/2" though the 1/2" tapes can be manually nursed back
> by alignment play.
>
> I used video tapes in the 8200's w/o any problem. All are still readable.
>
> Sample size was about 30 tapes in my case, not hundreds. YMMV

   MMDV (My Mileage Definitely Varied) :)  I too have some that are 
readable, mostly from Exabyte 8200s (2.3GB) but some from 8500s (5GB). 
At least they were still readable a few years ago.  These were 
definitely the exception though.  The company I worked for around '92 
had an 8200 and a bunch of video tapes when I got there, but had never 
set it up.  My first results were ok, but the second set of tapes were 
full of errors.  I guess the first time I just got lucky.  We got into 
the habit of running a head-cleaning tape after every two or three uses 
of the drive; that helped a bit.

   My boss insisted on getting an 8500, though I wasn't convinced of the 
efficacy of the technology.  I wanted to just stick with our trusty 
QIC-150 and use a bunch of tapes for incremental backups.  He wanted 
full backups every time (I think he didn't really understand the 
incremental backup concept) which made the 150MB QIC-150 tapes 
impractical.  Results with video tapes for the 8500 were terrible; not a 
single tape worked well.  We bought data-grade tapes (Sony QG-112M I 
think) and that improved things, but it was still pretty bad.

   At my next company we had a brief dabbling with an 8200 but replaced 
it with a 4mm DAT, with which I had had some experience at a small 
consulting job.  I liked DAT at the time, but hadn't really put volumes 
of data through it.  I wish I had, because I fought tooth and nail to 
get us a DAT drive at that company, but boy was that a mistake.  They 
were only marginally more reliable than the 8mm Exabytes all told.

   It took a few years of running double backups until we got a truly 
reliable tape system: DLT.  That was 1995, and I am still sold on DLT 
(and its descendants) now.  Super fast, super reliable.  My home 
network's backups are running to a 64-tape juke with four SDLT-220 drives.

   I also found your comment regarding 1/2" tapes interesting.  I'm 
assuming you mean 9-track, as there are many 1/2" tapes that aren't.  In 
my experience ("mileage"! ;)) 9-track is the only tape format that's 
anywhere near as reliable as a DLT.  Of course we're talking 150MB vs. 
200+GB per tape (for my current drives) so it's very much apples and 
oranges.  9-track tape reliability depends very much on the particular 
drive in use.  (though I suppose that's true for any kind of tape)

              -Dave

-- 
Dave McGuire
Port Charlotte, FL



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