ADSM-L

[no subject]

2015-10-04 18:11:36
Paul,

~ QUESTION: Does anybody else run their ADSM server on an AIX box and =
have
~ their database on a non-IBM drive? If so have you seen any problems =
like
~ the above before, in particular with SEAGATE drives?

There is no reason to use IBM drives only, as well as drives are 100%
functioning.
The advice to use IBM drives may be more than coprporate identity : AIX
team may have tested AIX with some set of hardware, and they surely have
tested IBM drives, while Barracudas were maybe not tested. While most of
disks will work with AIX on IBM computers, there may be some disks, or
some revisions of some disks, which will cause problems under certain
circumstances.

While I have no ADSM on AIX, we have some experiency with different hard
disks running on different computers under different OS-es (HP-UX,
SUN-OS, NT, OS2).
I run ADSM on OS/2 with mix of Barracuda=B4s and Quantum ATLAS-es.

The important  point is, the COMBINATION of Harddisk, its firmware,
cabling, scsi controller, its firmware, and software driver has to be
absolutely reliable.
Here we experienced few times problems wit certain combinations of the
above. While the systems concerned mostly worked OK, there were some
occasional errors when working for longer periods under heavy load. Most
of this problems appeared in systems using very quick disks - such like
Barracudas, but not always are the disks only were  to be blamed.

What can you do?

 - there are possibilities in alll flavours of Unix to watch soft errors on 
your disks. If
you have many - or some at all - soft errors on your disks, you may want
to tune your hardware. Check cabling, use shorter SCSI cables (even if
you are currently under the length limit), if the errors are related to
single drive only then replace the drive, ... Check if your Barracudes
are cooled properly. An overheated Barracuda will produce occasional
errors.

 - we believe most occasional problems we ever had with quick disks
raised from improper functioning of multiple command queueing. This is
the possibility for scsi controler to send more commands (thus command
queue) to hard disk, and the hard disk can then execute them in an
optimised way. We were obviously able to get rid of the problems by
installing newer firmware on either disk or disk controller, or by
updating the device driver (although I do not really understand the
influence of the latest - it helped some times).

 - If you already have newest firm- and software, try to down-tune your
disks.
 Shut the commang queueing on your disks off. If it does not help,
 decrease the maximum transfer speed between your controller and your
dsik. If it does not help.
 shut the cache on your disks off.

While this will slow your system particulary down, it will help you to
determine what your problem is.

 - Think about purchasing RAID subsystem for your database.





~ * The database now occupies 2xs the amount of space it did
previously!!
Sorry, I have no Idea what this could be caused by.


Juraj SALAK, Keba Banking, Linz, Austria


 ----------
~ Von: P.A Walmsley
~ An: Multiple recipients of list ADSM-L
~ Betreff: Database corruption??
~ Datum: Donnerstag, 12. Dezember 1996 11:57
~
~ I am running AIX4.1.4, ADSM server code 2.1.0.8 and various UNIX
~ clients.
~
~ I have been getting a number of page address mismatch errors on the
~ database from the ADSM server
~ e.g.
~
~    logical page 9208 (physical page 9464); actual 19191165991
~
~ resulting in the server terminating with an internal error BUF011.
~
~ I have a call currently open at the moment with IBM about it. Their
~ advice is to move the database to an IBM disc drive. It is currently on
~ a SEAGATE ST15230N. There are no indications in the error log of any
~ errors from the 3rd party disc. I have been talking with SEAGATE over
~ this and they confirmed that the firmware revision I have on the drive
~ is the latest for this particular drive.
~
~ QUESTION: Does anybody else run their ADSM server on an AIX box and have
~ their database on a non-IBM drive? If so have you seen any problems like
~ the above before, in particular with SEAGATE drives?
~
~
~ For your information I have done a dumpdb followed by a load/audit to
~ try and fix the problem. It gave some interesting 'features'
~
~ * To load my database which is almost 500MB in size I had to define a
~ space TWICE the size in order to get it to work.
~ * The database now occupies 2xs the amount of space it did previously!!
~ * The loaddb/audit eventually worked, did not use detailed=yes on audit,
~ but the number of  read errors reported now is actually worse!!
~
~ Thanks in advance,
~
~ Paul Walmsley
~
~
~
~
~
~
~ logical read
~

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