Re: ontape vs onbar: Changing NSR device block size

#1

Neil,

in addition to Martin's suggestion I would like to suggest an action plan
for one specific tape device.

The 'NSR device' parameter 'volume block size' is not displayed per
default when running command 'print NSR device'. This is actually a hidden
parameter, however, you will be able to set a value for this parameter. See
below.

For example:
You want to update the volume block size of tape device '/dev/rmt0.1' from
value <unknown> to <1024 KB>.

To update one specific NSR device and leave others as they are the
following NSR commands are needed.
- Start 'nsradmin [-s localhost]' to get the NSR server interactive mode
- Run the NSR command 'update type: NSR device; name: /dev/rmt0.1; volume
block size: 1024 KB'
-> The parameters will be displayed and you will be asked for 'Update?'
- Answer 'y'
-> The message 'updated resource id <number blabla>' will be displayed

HTH

Robert

Robert Seifert
__________________________________________________ _______________
IBM Deutschland GmbH, Software, Information Management Solutions

Elite VAR support engineer
Development Support for IBM Informix Products on-site @ SAP
c/o SAP AG, -TechDev05-,Neurottstrasse 16, D-69190 Walldorf, Germany

owner-informix-list (AT) iiug (DOT) org wrote on 18.08.2005 12:03:09:

Quote:

Hi,

I/O block size for write operations indeed cannot be configured
in ON-Bar. This is mainly because ON-Bar doesn't do the I/O
write operations. The storage manager is doing them, therefore
you need to configure blocksize there.

With ISM as storage manager try the following:

- as user root execute "nsradmin"
- nsradmin> print NSR device
- nsradmin> update volume block size: 1024 KB
-- this will ask you several times (once for each device ?)
-- whether you want to update the value.
-- answer with "y" or "n" as appropriate ...
- nsradmin> quit
-- to leave nsradmin utility

All this is a bit cryptic, but it seems to work (at least it changes
the configured values for the device(s)).

Regards,
Martin
--
Martin Fuerderer
IBM Informix Development Munich, Germany
Information Management

owner-informix-list (AT) iiug (DOT) org wrote on 17.08.2005 15:11:51:
"Martin Fuerderer" <MARTINFU (AT) de (DOT) ibm.com> wrote in message
news:1124275387.367f6e33d3f4593be9c8290f7a8a7071 (AT) teranews (DOT) ..

Hi,

if you want to get to the bottom of this I think it is time to
analyse,
where the bottleneck is. Ontape is rather simple, writing directly to
a (usually local) tape.

ON-Bar involves several components and you should look at each
of these and the communication between them. You can start with
the ON-Bar activity log file to check if there is a certain "phase"
in
the backup that takes longer than expected. You can also
check/compare to the respective lines in IDS message log. You
may also want to look into ISM log files, but you may find that
messages there do not exactly (time-) match with messages from
ON-Bar.

It just starts off slowly, and consistently writes out slowly, compared

on
ontape. There's no particular phase in which it's slow, the throughput

is
just consistently a quarter the speed on ontape's.

I should stress again here that both ontape and onbar are writing to
*disk*
in this comparison.

If onbar is inherently slower, then it's slower. I'd just never
noticed
it
as being so before and am very surprised.

As I say. my hunch is still that it's all down to being able to
configure
TAPEBLK in ontape, but not onbar ...

sending to informix-list

sending to informix-list

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Re: ontape vs onbar: Changing NSR device block size

comp.databases.informix comp.databases.informix

Re: ontape vs onbar: Changing NSR device block size - 08-18-2005 , 08:05 AM