Some time ago, I posted the following query:
> Hi. In my research group, we back up as frequently as we can, but still
> run into problems because of the unreliability of our backups. We use
> an Exabyte 8200 8mm drive. We go through 8mm tapes like crazy, because
> they keep dying with media errors after minimal use.
>
> We use predominantly Maxell and Fuji (112m length) tapes, because that's
> what we can get from University Stores or local vendors. But quite
> frequently, these things are dead after only two "backup-catalog" runs.
> Today, I needed to retrieve a file from tape, and had to go three backups
> back to get it, because the tapes kept failing with "media errors." In
> the past, it's been impossible to retrieve files, because all the backups
> of a certain disk were shot.
>
> Thinking that maybe the Exabyte drive has problems, I replaced it with a
> new one. The problem persists. I can only presume that I'm buying terrible
> tapes. Who makes good ones? In what lengths? Where do I find them, and
> how much might they cost?
>
> To keep any discussion from cluttering up all three newsgroups I've
> cross-posted this to, please email me with any advice you have, and I'll
> post a summary.
>
> Thanks much. This is really driving me crazy.
A lot of you did send email (thanks!), and I wrote back most of you.
Here's the summary.
1. The biggest concern of most people who responded was whether or not
I was using data grade 8mm tapes, as opposed to 8mm video tapes.
I have been using exclusively data grade tapes, so that wasn't my
problem; but it's worth noting that this is an important possible
problem. Several people noted that they experienced problems
similar to mine while using video grade tapes; the problems went
away when they switched to data grade tapes. Again, this wasn't
my problem -- we use only data grade tapes -- but the mail on
this issue was informative. There were a variety of reasons quoted
for avoiding video grade tapes which were quite explicit. It should
be noted, though, that a few people said they used video tapes
regularly, with no problem.
2. The second biggest concern people wrote me about was making sure
the drive is clean. We do run cleaning cartridges on our
drive, but perhaps not frequently enough. We've been cleaning
every four weeks or so, but our data thruput is probably too
high for such a slow cleaning rate (about 48 GB in that time
frame), so we've started cleaning more frequently.
It was also stressed by several people that it's important to
clean the drive immediately after a media error. This is
something that we HADN'T been doing, and so is very good to
know. Often, our tape failures would occur in bunches, so
this makes sense.
Regarding cleaning, one person wrote:
> never use camcorder head cleaners, they will destroy your heads,
> and probably void your warranty (if your supplier has any brains).
This was rather timely. We hadn't used camcorder head cleaners,
but we were recently shipped one by mistake. I'd been wondering
whether it was ok to use or not.
3. Some people did swear by certain tape vendors, or swear at others. Many
people use Exatapes or Sony QG112MA data grade tapes exclusively,
with no problems. Several people hinted that these two may be the
same tape, under different brand names. I include some of these
comments:
> I always use 3M D8-112 data tapes on an Exabyte 8500c. Very rarely
> do I get errors, and some of these tapes are ~20 generations old.
> I get mine from N E Data, but they're easy to find. I think I pay
> ~$9.00 per tape.
> I am using Sony 112M tapes without any problem.
> We have found that the Exabyte tapes do well for us. We use them
> over and over again thru the backup cycle. I have never had any
> problem with restores. Some of our other sites have used the Sonys
> and say they do well too. Our field engineer from Prime says that
> a lot of the other tapes on the market are too abrasive for the
> tape heads of the tape drive and mess them up.
> We use ExaTape 112m (from Exabyte), or Sony QG112M.
> Just and FYI for you: We have 4 Exabyte 8505 drives. We use
> Maxell brand 8mm (112M) Data 8 tapes. And we use the Exabyte brand
> cleaning tapes. We have no problems with the Exabyte brand cleaning
> tapes. We backup quite a bit of data (100 machines or so @ approx.
> 1 GB per machine). Except for the occasional errors with the tape
> drives (1 every 6 months or so-this is a guess) we have no other
> problems. And i must say, i have been overall impressed with
> the Maxell brand 8mm tapes. I will occasionally get a tape that
> gets eaten in the tape drive, but that doesn't happen very often.
> And i must say that i have NEVER (ok, only once) had a problem
> restoring data from a tape. Unfortunately, someone usually deletes
> something every 1 1/2 weeks or so, so i restore "stuff" quite
> often. Also, we have used these tape drives and Maxell brand tapes
> for around 1 year now!!
> We have been using FUJI P6-120 8mm tapes without problems. We
> also clean our Exabyte with an 8mm cleaning tape about once per
> month. We also clean it immediately after noticing a media error
> (rare).
(I think the P6-120's are video tapes -c)
> We have several 8505 exabytes, an 8500 stacker and an 8200. We
> use memorex MRX-112m (P/N 3202-3016) or BASF extra 8D-112m and
> very rarely have any problems. Although we rarley rorate our
> backups (we backup approx 40GB weekly and incrementally), we
> reuse tapes for data transfers etc, but still have very few
> problems.
4. I dismissed that the problem was with the drive, because I'd swapped
the drive with a new one and the problems persisted. However,
there was some controversy about the intrinsic quality of the drives.
One person wrote:
> the EXB-8200 and EXB-8500 drives are probably the most reliable
> tape drive we sell and maintain. We have more than 200 sites
> running them with very little problem.
but another wrote:
> The Exabyte 8200 drives are less reliable than the Exabyte 8500
> drives; you might want to consider upgrading. Also, in my
> experience "media error" can indicate drive problems. Since
> Exabyte drives are repackaged and sold by everyone from here to
> Lower Slobovia, vendor quality, and drive packaging quality,
> varies greatly.
Opinion #3:
> Sounds like an Exabyte ok. The solution (in my opinion) is not new
> tapes, but rather a new tape drive (and not another Exabyte!).
[ detailing of other options deleted ]
and still another wrote:
> No, the drives are terrible. I've seen eight exabyte drives die
> mysterious deaths in the last year. Most of them chew tapes.
> Some go bonkers. Some like to lock up the SCSI bus. I've found
> them to be totally unreliable.
4. One person wrote that one shouldn't use "dump" on active filesystems;
the tape backups are then unreliable. I'm not using dump for
most of these backups; but still thought I should pass this
along.
Anyway, thanks to everyone who responded. We have increased the frequency
of our cleanings, and are giving the Sony 112m tapes a shot.
-- Chris Metzler Department of Physics, University of Michigan 313-764-4607 (office) Randall Lab, 500 E. University 313-996-9249 (home) Ann Arbor, MI 48109-1120 USA E-MAIL: metzler@pablo.physics.lsa.umich.edu"It does me no injury for my neighbor to say there are twenty gods or no god. It neither picks my pocket nor breaks my leg." -- Thomas Jefferson
This archive was generated by hypermail 2.1.2 : Fri Sep 28 2001 - 23:09:11 CDT