ADSM-L

Re: 3592 tape read performance

2006-07-31 08:14:06
Subject: Re: 3592 tape read performance
From: Rainer Wolf <rainer.wolf AT UNI-ULM DOT DE>
To: ADSM-L AT VM.MARIST DOT EDU
Date: Mon, 31 Jul 2006 12:58:49 +0200
Hi Thomas,
3592-J1a, tsmserver 5.3.3.2 on Solaris10
we have the same thing happened - also removed 2 or 3 tapes
from the library.
It was really annoying because a tape may happen to be reading
24 hours constantly reading but with some kBytes per second.

In our case it seems to be possibly both our old firmware in the
tape-drives and also the tapes ( here: ibm labeled - not the fujii ).

The tape support technician who checked the drives described
2 possibilities that may happenen at the tapes:
one thing is that the builtin brakes on the tapes may seldomly have a
malfunction leading to heavy positioning tasks of the drive.
The other thing is that the tape-material is slightly stuck - that
may happen with brandnew tapes and that might disappear once using the
tape at the whole length.

The firmware -update here has been a little bit complicated, because
first the drives seems to be gone.
After reset of the drives also the server-system had to be restarted.
Also you should check the latest tape-driver (IBMTape) .

Because now anything seems to be fine we may test again the
ploblem-tapes if they now work better .

....
Using the latest tape-drive and solaris-os Version it is very fine
for me that the unix 'iostat' - utility now is friendly showing
the current statistics of the tape-drives too  ... not only of the disks as 
before our update.
I currently localized one drive running a migration process and constantly 
running
with nearly 100 % busy and a write speed roughly around 5 MB/s over the time.
Moving that process to another drive ( same data , same destination tape-volume 
)
it shows to run normal and being 10 times faster. No errors at all - Just 
called the service ....
... so you may also take a look at iostat ( eg 'iostat -x 5' ) if you also
can see the drives there.

for example that is really no 'problem-output' :-) :
                  extended device statistics
device       r/s    w/s   kr/s   kw/s wait actv  svc_t  %w  %b
IBMtape6     0.0  348.3    0.0 89166.2  0.0  0.6    1.7   0  58


Greetings
Rainer





Thomas Denier schrieb:
We are seeing increasingly frequent problems reading data from 3592
tapes. TSM sometimes spends as much as a couple of hours reading a
single file with a size of a few hundred megabyes. In some cases,
TSM reports a hardware or media error at the end of that time. In
other cases TSM eventually reads the file successfully. In the
latter case there are, as far as we can tell, no error indications
at all: no TSM messages, nothing logged by the OS, and no indicators
on the front panel of the tape drive. In some case the same tape
volume suffers this type of problem repeatedly. The problems seem
to spread roughly evenly over our whole population of 3592 drives.

We have just removed one 3592 volume from service because of
recurrent read problems, and are about to remove a second volume
from service. We only have about 120 3592 volumes, and losing two
of them within a week is disturbing, to put it mildly. The
possiblity that the volumes with non-recurring (so far) problems
will eventually need replacement is even more disturbing.

Our TSM server is at 5.2.6.0, running under mainframe Linux. The
3592 tapes drives are all the J1A model.
Does anyone have any suggestions for getting to the bottom of this?




--
------------------------------------------------------------------------
Rainer Wolf                          eMail:       rainer.wolf AT uni-ulm DOT de
kiz - Abt. Infrastruktur           Tel/Fax:      ++49 731 50-22482/22471
Universitaet Ulm                     wwweb:        http://kiz.uni-ulm.de

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