SUMMARY: Tape media lifetime

From: Robert Schreiber (
Date: Tue Mar 10 1992 - 15:52:49 CST

Hi Sun-Managers,
My original Question:
> Hi SUN-managers,
> What do you think, how many times can a video tape cartridge for the
> Exabyte tape drive be used to reliably store my data?
I have received a lot of information.
There are two values which seem to be interesting:

Average: 3 Years or 50-150 times used
Worst case: failed after two or three times

It seems like it's worth it to check a tape's content after saving
data on it.
SUMMARY: Exabyte tape and reliability
SUMMARY: 8MM tape for backups
SUMMARY: 8mm media reliability
SUMMARY: Exabyte tape aging
SUMMARY: Exabyte 8200/8500 driver

The general concensus I get is three years. In a temp and humidity
controlled room. We have some 2.3 gb tapes 2.5 years old and read them
with no problem. Of course we have some 10 year old nine track tapes.
Some we read no problem. others are useless.
Most companies ( 3M, verbatim, sony) recommend a tape maintence program
(dubbing to new tapes ) start at 2.5 to three years of tape life.

in the basic guidelines for storage life are:
tape 3 years
erasable optical 10 years
write once optical 100+ years.

Malcolm Strickland

We have 4 video-grade 8mm tapes (Monday - Thursday) that we have been using
once a week since April 1989, which is 3 years * 52 weeks = 156 uses. They
are still working fine, and the number of retries/megabyte dumped seems to be
fairly constant over time.

In general, we swap out our weekly tapes after about 5 uses, but that's just so
that we have periodic "save" tapes that we don't overwrite.

Drew Montag

I've been using some of our tapes for almost two years. Many of the tapes
have been re-used about 50 times (wild guess).

We use SONY P6-120MP exclusivly. About 4% of the tapes (3 in 50) exhibit
failure in the first few uses and are retired to some department's camcorder, the others go on to become old friends.

        Daryl Crandall

When a restore fails, you will then know its time to buy a new tape :-)

Seriously now, I would never use the same tape for over 1.5-2 years....

Dimitris Koumanakos

We use 8mm tapes extensively for Vax backups and are just beginning
to use them on Sun servers. Have tried several brands and now
using TDK HS120 video cassettes.
Most tapes have been user 20 to 30 times without failure but a few
have failed after 3 or 4 uses.

Bob Reardon

We have been using Sony 8mm P6-120MP video tapes for about 2 years
with no problems, except for an occasional transport mechanism failure.
At this point, most of our tapes have been used 3 times for dumps, but
many have been used for restore 8-10 times.

Recently, we decided to switch our monthly dumps to the Sony D8 8mm
QG-112M Computer Grade Data cartridges. A recent blurb in "Sun Observer"
indicates that they can handle up to 1,500 pases without unrecoverable
media error and have a shelf life of > 30 years.

The summary below is from a previous sun-managers query on tape
reliability from Doug Neuhauser.
Subject: SUMMARY: Exabyte tape and reliability

Frank Lowe (


   About 15 to 20 times reliably or until you start getting a lot of
read/write errors.

Computing Facilities

I test mine reguarly. I stopped testing at 20 reuses and replace them
around that point because it's hard enough to believe I can stick 2GB
on one of those dinky tapes...let alone reuse them 20 times.

 We use Sony.

From: David Fetrow <>
After makeing a backup, our script reads the tape to make sure
things appear to have been backed up okay.

We use tar and prepend each saveset with a 1K header -- that's all we actually read, but it's enough to give us confidence that the tape is good. You should be able to do something similar with dump (if that's what you use).

-- Steve Harris - Eaton Corp. - Beverly, MA - uunet!etnibsd!vsh --------------------------------------------------------------------------

I don't know but I've used them for backups for about 15 times so far and no problem so far. Would like summary. - thanks. From: (Operator) --------------------------------------------------------------------------

From: (J. Matt Landrum)

Here is a copy of Don Cunningham's Summary. I disagree with his result. I think they can be used more times than he says. It really depends on how important your application is. I've been doing backups on the same 2 tape drives for 2 and a half years (the same tape gets used once every 4 weeks and they sit out in my car in the sun sometimes) and have only had trouble with one tape. Also, when doing quarterly dumps and backups before O/S upgrades, I have never had a problem.

Please look at: SUMMARY: 8MM tape for backups --------------------------------------------------------------------------

>From millidc!indigo!djm@uunet.UU.NET Thu Dec 5 11:42:43 1991

We have some that we have been using once a week since April 1989, which works out to 32 months * 4 uses/month = about 256 uses, and they are still working fine. We have used a total of 50 Sony P6-120MP tapes so far, and only one has gone bad. --------------------------------------------------------------------------

From: Al Lichty <>

I have heard a lot of opinions regarding the need to use only specially graded tape for 8mm backups, but my experience is quite different. I have been using Sony video tapes for about 2 years now - I have 15 tapes that I use for full backups every wek night (1 tape per night) that have not failed me yet. My guess is that each tape has been rewritten at least 30 or 40 times now and they still work fine - the last time I needed one was about 3 weeks ago when I lost a disk on a dataless client. The restore went with a problem :-)

Al Lichty -------------------------------------------------------------------------- I am currently using the video grade cartridges for my daily backups. I have been using the same cartridges for about 8 months with no problems. But I do test them regularly. It must depend on the quaility.

Debby Wyron

-------------------------------------------------------------------------- >From Thu Dec 5 12:34:01 1991 We use are tapes hundreds of times but they are the good quality tapes. Stay away from the cheap ones they lose bits after 6 months.

Also /bin/mt -f /dev/... status.

If anything bad appears in the status, then chuck the tape and redo with another.


DISCLAIMER: I have no connection with the sales force at Delta or any of it's distributors. The information on Delta products is provided as a service in the course of answering a technical question.

Here at Delta we recommend no more than 50 passes. Each time you write OR read the tape, it counts as a pass. After 50 passes the percentage of tapes that are no longer good has risen to about 30%.

An alternative to the blind retirement of tapes is a program of monitoring the quality of the tape as it is written. This can be done manually or by means of an automated tool like the 'smtmon' program available from Delta.


I have 8mm Sony tapes that I have used at least 20 times with no problems. TDKs tend to die after about 5 uses, at least in my short (1 yr.) experience. I have had to trash only one Sony tape in all that time.

I do nightly incremental backups using 'dump' and a full backup once a week, all automated using fairly simple shell scripts and 'cron'. I change tapes once a week (although, given the new Seagate Elite 1 1.6G (1.2G usable) hard drive we just purchased, probably will have to go to two) and have 10 tapes that I cycle through, one used (currently) every other month. The tapes used 20+ times I refered to earlier are used for temporary transfer of files to other sites, migrating files from one drive to another, etc.

Joel L. Seber | Dry humor is wasted around here. --------------------------------------------------------------------------

>From Thu Dec 5 13:00:22 1991

We've exceeded 20 times and we didn't get any problems... --------------------------------------------------------------------------

>From Thu Dec 5 13:29:24 1991

I can't give you official information - but we've never had problems with tapes written many more than 5 or 6 times. We replace them when the cause trouble. --------------------------------------------------------------------------

>From Thu Dec 5 13:51:58 1991

I have been using 8mm tapes on a rotating basis for dumps for years. I would guess that I have more than 30 uses on some of the tapes. Tapes used have been standard video grade Sony MP120. We do find an occasional bad tape, but at $5 or $6 each, who cares? The bad tapes are defective right out of the box and I have never seen a tape go bad after it was successfully written, except for a few that were physically "eaten" by the transports.

Lewie Wolfgang --------------------------------------------------------------------------

We've user the inexpensive video tape for two years, overwriting on some of them dozens of times. Although we seldom need to read back from these frequently used tapes, we have never seen an error that appeared to be caused by "worn out" tape. But we'd like to hear about any more formal testing done on them.

Ev Schell -- Molecular Biology Computing Center, U of Minn. --------------------------------------------------------------------------

i would hope that a tape can be reused more than five to six times. some of our daily dump tapes are probably beyond ten times that, with no write errors. since the exabytes do read after write, i assume we are safe.


How many times your tape can be written on will depend on a number of things. I suspect that if you can regularly "stream" your exabyte rather than frequently force it to pause, your tapes will last longer. In the past, I have used my video grade Sony tapes many more than 5 or 6 times.

For my UNIX backups, I was using the APUNIX Exabyte software. Part of that package is a program called 'xbinfo' which will tell you the number of errors during the previous tape operation. By watching those numbers you can tell if your drive is dirty or if your tape is getting old. I believe the xbinfo program requires the APUNIX Exabyte driver on a Sun.

I have also seen Exabytes fitted with LCD displays that give error rates.

I'm not sure if the SunOS 4.1.1 mt 'status' command reports error rates. I think that watching error rates is probably the best way to be sure, though.

Brian --------------------------------------------------------------------------

I don't have any official info for you, but I have used those Sony tapes for backups hundreds of times. I've probably only had 2 or 3 go bad in 2 years. Don't let the exabyte people fill you with a bunch of crap. They just want to sell you their media at a greatly inflated price. Of course if one of my tapes goes bad, it's no big deal since I do backups 5 times a week and save them for a number of weeks. It depends on how crucial your data is I suppose.

-------------------------------------------------------------------------- Anyway, the life-time (how many times it can be written/read) of an 8mm video grade tape is very subjective to the way the tape is handled. Assuming normal human handling, as in our set-up (we don't use gloves etc) the tapes that we use have never failed (well, not yet). The drives though have been cleaned fairly regularly, say every couple of months and the drives are used every night with one tape in each. We rotate the tapes for nightly backups and these tapes are written on very regularly. Doing a quick {sort} etc on our list of backups (we do keep a history) I see that one tape has been written on 12 times. Whether this is safe or not I'm not sure and also I'm not sure if that tape was ever used in a restore.

Maybe you'll (or a tape manufacturer) will recommend us buying more tapes and of higher (data grade) quality. I await the summary.


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