SUMMARY: Bad Luck with 8mm tapes.

From: karl@water.ca.gov
Date: Wed Oct 05 1994 - 05:57:34 CDT


My original post:

>
> What is the most reliable/cheapest/best media
> of backup you have had good luck with?
>
> We use Exabyte 8500 drives (8mm) with compression
> and seem to have a failure reading back the Exabyte
> certified data quality tapes every 30 tapes or so.
>
> Have you had better luck with 4mm, CD, another type
> of drive, reel, Optical, etc for a backup method? (We
> use Legato Networker for distributed and various types
> of Unix machines backed up to a Sun Server).
>
> Thanks for sharing your experiences (good and bad).
> I will post a summary.
>
> --Karl

Thanks for all the responses.

Most people had good things to say about 8mm (the
majority or responders liked 8mm as long as
compression was turned off.)

4mm DAT tapes and Digital Linear Tapes seem to be more
reliable, but only a few people could confirm this
with their experience.

I broke your responses down into three categories
for summary:

--------------------------------------------------
1) We like 8mm, are you using it correctly ?
--------------------------------------------------

>From rgjj490@wadnr.gov
--------------------------------------------------
Store the tapes on edge.

>From digit.com!bharrell@dti.portal.com
--------------------------------------------------
Clean the tape every 20 hours.

>From weitzel@burke.com
--------------------------------------------------
clean every 15 gig's of use with out fail.

>From jamesm@matrix.newpaltz.edu Thu Sep 29 18:00:08 1994
>From lau@nwnexus.wa.com Thu Sep 29 14:37:35 1994
--------------------------------------------------
Suggestions that it might be a hardware
problem with the drive, or bad tapes.

--------------------------------------------------
2) 8mm Exabytes work better without compression:
--------------------------------------------------

>From kastnerb@njc.org Thu Sep 29 20:13:06 1994
--------------------------------------------------
I have been using an Exabyte 8200 for over 5 years and have had only one bad
tape experience. I don't use compression which I realize can be a problem
with large disk systems. We just go through a few more tapes.

>From gcp@lnsp00.com Fri Sep 30 00:55:36 1994
--------------------------------------------------
I think compressing increases the chance of a tape being unreadable (?)
- I certainly believe you shouldn't do important backups/archives in
compressed form.

>From @ohmg.hydro.on.ca:rob.e.allan@hydro.on.ca Fri Sep 30 04:55:15 1994
--------------------------------------------------
We use Exabyte brand tapes on our 8500 and have had no problems.
We don't use compression..

>From merccap!clark!saieva@uunet.uu.net Fri Sep 30 07:58:24 1994
--------------------------------------------------
We like the 8500 drives but we don't use compression. We're currently using
8mm data grades tapes from 3M and haven't had problem.

>From epl@Kodak.COM Fri Sep 30 18:48:03 1994
--------------------------------------------------
We use 8mm withOUT compression and have had VERY good luck. There is a very
good (in Solaris 2.3) interaction between the tape drive and the system, where
soft re-try errors are display to syslog.

I feel that compression, whether tape or disk is an accident looking of a place.

>From crimson!cab@aluxpo.att.com Thu Sep 29 12:55:35 1994
--------------------------------------------------
I've been in an environment that uses Exabyte 8500 drives and Sony
and Exabyte tapes. The drives were used on Sparc 1+s, 2s, and 10s.
 
First off, the 8500s do NOT work reliably with SS2 and SS10 machines
running compression. The maintenance people we have hate the 8500's
because it's hard to put a finger on what the problem is.
 
We have put our 8500s on SS1+ machines and also have one on a 4/280.
The 8500s work much better on the SS1+s. Tapes are still a factor
though. For a while we could use a Sony 8mm that was fresh but using
a demagged Sony caused headaches. We finally figured that is you did
multiple stats and eoms prior to the dump that it would work. If you
kept the tape in the 8500 and did not rewind or offline it all was
well. Start the procedure over and you were back to headaches.
Even with fresh Sony's though we still saw problems.
 
We switched to Exabyte 8mm tapes (more $$) and using them once (fresh)
works out fairly well.
 
If you run without compression that also appears to make things run
smoother. The trick with compression is that it is not constant.
It varies depending on the data. When the drive is writing you can
watch the display and see it change.

In the near future my site will probably go with a stacker and NO
compression. I just felt that if I could share my experiences it
may save somebody else some grief.
 

--------------------------------------------------
3) Digital Linear Tape drives are better, but more expensive.
--------------------------------------------------

>From ian@sfu.ca Thu Sep 29 13:38:30 1994
--------------------------------------------------
We use DLT (Digital Linear Tape) tape drives. They stream at over 1MB/sec,
store 10GB uncompressed, 20GB compressed, and exhibit (for us) zero problems.

>From nitkin@ptdcs2.intel.com Thu Sep 29 19:19:26 1994
--------------------------------------------------
Digital Linear Tape (DLT) is your best choice, but it has a price tag.
As usual, you get what you pay for.

Thanks again to all who responded:

>From crimson!cab@aluxpo.att.com Thu Sep 29 12:55:35 1994
>From weitzel@burke.com Thu Sep 29 13:37:02 1994
>From ian@sfu.ca Thu Sep 29 13:38:30 1994
>From lau@nwnexus.wa.com Thu Sep 29 14:37:35 1994
>From plan_sun-request Thu Sep 29 15:09:27 1994
>From jamesm@matrix.newpaltz.edu Thu Sep 29 18:00:08 1994
>From tmornini@sun630mp-le0.infomania.com Thu Sep 29 18:48:43 1994
>From nitkin@ptdcs2.intel.com Thu Sep 29 19:19:26 1994
>From mikepb@Synopsys.COM Thu Sep 29 19:40:29 1994
>From kastnerb@njc.org Thu Sep 29 20:13:06 1994
>From digit.com!bharrell@dti.portal.com Thu Sep 29 21:01:46 1994
>From gcp@lnsp00.com Fri Sep 30 00:55:36 1994
>From martin@gea.hsr.it Fri Sep 30 02:00:51 1994
>From jam@philabs.Philips.COM Fri Sep 30 03:46:51 1994
>From @ohmg.hydro.on.ca:rob.e.allan@hydro.on.ca Fri Sep 30 04:55:15 1994
>From worsham@aer.com Fri Sep 30 06:19:51 1994
>From uucp@ucs.att.com Fri Sep 30 07:08:06 1994
>From rkh Fri Sep 30 09:54:46 0400 1994 remote from eng.ucs.att.com
>From MCCALLD@sonoma.edu Fri Sep 30 07:30:01 1994
>From merccap!clark!saieva@uunet.uu.net Fri Sep 30 07:58:24 1994
>From rgjj490@wadnr.gov Fri Sep 30 10:15:38 1994
>From epl@Kodak.COM Fri Sep 30 18:48:03 1994

--Karl



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