May be the following question is more hardware than Unix related,
sorry about that, but perhaps I can hear about some experiences
We connected 2 Exabyte drives (Eliant-820/EXB 8507) to an AXP 4/166
workstation under Unix V4.0-B. (First we got some wrong information
how to generate the driver. But then I got the proper entries for
ddr.dbase so that I don't believe that it is a software problem any
more)
We have written several 100 tapes with experimental data on other
Unix systems with EXAs 8500. Every tape has about 4.5 to 5 GB of data.
The tapes we used are QG-112M Fujifilm. We had no problems until now.
When we tried to make backup copies of this data tapes on this
workstation on brand new tapes of the same kind, exept in a few cases
the target tapes were full after transfering about 2.5 GB.
(Always cleaning etc.. Reading of our data tapes was no problem on
the Eliants)
Analysis of such a tape by people from Exabyte gave the answer
"The format used is 8500c. as you use a 112m cartridge with a
max capacity of 5gb uncompressed, and as you saved up tpo 6.7gb of
data on the tape, it is quite normal.
I did a transfert of the data on another tape and found out that
the ECC use was twice as much as the maximal admitted."
with the recommendation "use the original Exabyte tapes" (a factor of
two more expensive - and we need several hundreds!)
Indeed tests with original Exabyte tapes gave
- on the 160m Exa-tapes I could write 7.6 GB of data
Regarding 112M Tapes this means that 5.2 GB would fit on a tape -
this would cover our needs
- There was an othe argument that tapes because of dirt during fabrication
are getting better during the first 10 times of usage - therefore
I used one tape several times:
1.
2. 2.467 GB Data copied to it
3. 2.489 GB (cleaning also done)
4. 2.504 GB
5. 2.509 GB
Ok it got better, but less then I hoped ...
My question now is, is this really only a quality problem of the
tapes we used (QG-112M, Fujifilm)
- we have written several hundreds of these tapes on normal EXA
8500 drives (without problems) with up to 5 GB (just these
ones we want to copy now)
- therefore they have proven their quality already
or
- could it be that the firmware of the new Eliant-820 /EXB 8507
is somewhat over-sensible?
(see the above mentioned analysis "the ECC use was twice as much as
the maximal admitted.")
(Unfortunately the new Eliant drives were offered us as a (better)
replacement of the old 8500s, which we could not buy anymore)
Otto
-------------------------------------------------------------------------
| Dr. Otto Titze, Kernphysik TU, Schlossgartenstr. 9, D-64289 Darmstadt |
| titze_at_ikp.tu-darmstadt.de Tel: +49(6151)16-2916,FAX:16-4321|
-------------------------------------------------------------------------
Received on Fri Nov 14 1997 - 18:44:54 NZDT