IDS Forum

Re: IDS 7.31 migration HPUX to AIX ?

Posted By: Tilman Model-Bosch
Date: Tuesday, 20 January 2004, at 6:57 a.m.

In Response To: IDS 7.31 migration HPUX to AIX ? (PETER SIEGEL)

Dear Peter

I have attched two SAP Notes regarding Informix IDS on AIX .
The topics of the notes are generic , though .

Regards
Tilman

SAP-Note No. 675173
Short description: Informix error 25587 on AIX 5.x
----------------------------------------------------------------------------


Symptom
-------
Work processes terminate sporadically with Informix error -25587 on
AIX
5.1. Sometimes work processes may hang.

Other terms
-----------
IPC, link, shared memory, -25587, network, POWER4, PTS bug 161668, AIX
5

Reason and Prerequisites
------------------------
You are using AIX 5.x with a POWER4 processor. SAP work processes (WP)
terminate sporadically with error 25587 'Network receive failed'.
There
are corresponding entries in the syslog or the WP log file (dev_w*).
This only affects work processes using the Interproces Communication
Protocoll (shared memory link) for communication with the database
server.
This is caused by error PTS 161668 in the Informix-ESQL/C libraries.

PTS 161668
SHARED MEMORY CONNECTIONS HANG ON AIX POWER4 SYSTEMS

Solution
Only use TCP/IP as a link log.

o Convert the database to a TCP/IP link



Create a new service in the file /etc/services as a user "root"
and call it "sapinf<SID>a"

(Caution: use a service number that has not been assigned
yet!).

Note that with activated NIS, NIS+ or a similar service the
change must be made in the respective master file.

Example:

If your system is called C11, for example, you should call the
new service "sapinfC11a". The section from the /etc/services
would now appear as follows:

sapinfC11 4461/tcp
sapinfC11a 4462/tcp


Change the entry for the shared memory link as the user
"informix" in the sqlhosts file ($INFORMIXSQLHOSTS).


Example:

If your system is called "C11", for example, and the database
server is called "dbhost", this would produce the following
entry
in the sqlhosts file:

dbhostc11shm onipcshm dbhost sapinfC11

Replace the log type as follows in the line:

HPUX/AIX/LINUX/DEC: onipcshm -> onsoctcp
SOLARIS: onipcshm -> ontlitcp

Replace the service to be used with the newly created service,
in
other words replace "sapinfC11" with "sapinfC11a". The result
should look as follows:

HPUX/AIX/LINUX/DEC : dbhostc11shm onsoctcp dbhost sapinfC11a
SOLARIS: dbhostc11shm ontlitcp dbhost sapinfC11a

The change to TCP/IP as the link log does not adversely affect
performance.
If you then comment out the parameter NETTYPE for the SHM link in the
Informix DB configuration file $ONCONFIG, this has the side effect
that
the address space is used better. This may offer substantial benefits
with 32-bit database servers in particular (see note 407543).

-----------------------------------------------------------------------------------
-----------------------------------------------------------------------------------

SAP-Note No. 407543

Short description: AIX: Shared Memory Management with Informix


Symptom
-------
No more SHM segments can be allocated on IBM AIX. This generally
concerns 32-bit DB servers only.

Other terms
-----------
memory allocation, shared memory, ONCONFIG. Informix, configuration

Reason and Prerequisites
------------------------
32-bit processes on AIX can create only 10 (AIX<4.2.1) or 11 Shared
Memory (SHM) segments. The size of a SHM segment is variable, however,
every SHM segment uses an address space of 256MB. SHM segments larger
than 256MB use multiple address spaces of 256MB. Thus, 32-bit
processes
have a maximum address space of 11 * 256MB = 2.75GB available for
shared
memory.
A SHM segment created with a size of 260MB (266240 KB) for example,
would thus use 2 * 256MB (=524288 KB) of address space; however, the
useable memory for the process is only the 260MB with which the SHM
segment was created.

Thus you should make sure that SHM segments are only created with a
size
that is a multiple of 256MB.
64-bit processes also use 256MB of address space per SHM segment,
however, far more SHM segments can be created.
Solution

Make sure that the 'resident' SHM segment of the Informix DB
server is slightly below a multiple of 256MB.
The size of the RESIDENT SHM segment is determined through the
ONCONFIG parameters PHYSBUFF, LOGBUFF, BUFFERS, and LOCKS.
PHYSBUFF and LOGBUFF are given in KB. BUFFERS determines the
size
of the database buffer in pages. In AIX, the size of a database
page is 4KB.
The parameter LOCKS determines the number of available database
locks, every LOCK requires 44 bytes of memory.

SHMVIRTSIZE should be a multiple of 262144KB.
!Caution: Under AIX 4.3, the maximum size for a single SHM
segment is 2097152KB (2GB).

SHMADD should always be set to 262144KB.

Use only TCP/IP for the connection protocol.
The connection to the DB server can be made over TCP/IP or also
over IPC (i.e. shared memory) locally. In the latter case, the
db
server creates a so-called 'Message' SHM segment. This is
generally small, but uses 256MB of address space nevertheless.
If 'Shared Memory' is a bottleneck, you should use TCP/IP for
connection setup locally as well; in that case you can do
without
the 'Message' SHM segment. For this, set the parameters
DBSERVERNAME and DBSERVERALIASES to TCP/IP connections from
$INFORMIXSQLHOSTS and delete the parameter NETTYPE for the IPC
communication from the $ONCONFIG. Please see note 111876
describing the procedure for connecting a 32-bit kernel to a
64-bit DB for more information.
No negative consequences on the performance need to be feared.

Check the size of the requested shared memory with the command 'onstat
-g seg' and 'ipcs -m -a'.



--
Tilman Model-Bosch
IBM Data Managment Solutions, Informix Advanced Support
c\o SAP AG
TECHDEV 05
Neurrotstr.16
69190 Walldorf






"PETER SIEGEL"
<psiegel@us.ibm.c To: ids@iiug.org
om> cc:
Sent by: Subject: IDS 7.31 migration HPUX to AIX ? [2445]
forum.subscriber@
iiug.org


01/19/2004 08:59
PM





Hi all,

I have a customer planning to migrate a large IDS 7.31.UD4 OLTP application
from HPUX 11 to AIX 5.2 (32 bit)
I am looking for any experiences,resources, articles or information
addressing AIX specific IDS bugs and gotchas [as well as that specific
migration]
Is there a recommended version of IDS 7.31 for that platform? Is there a
preference for either 32 or 64 bit?
I'm really interested in anything information I can find on IDS on AIX 5.

Thanks in advance,

Peter

Messages In This Thread

• IDS 7.31 migration HPUX to AIX ?
  PETER SIEGEL -- Monday, 19 January 2004, at 2:59 p.m.
  • Re: IDS 7.31 migration HPUX to AIX ?
    Tilman Model-Bosch -- Tuesday, 20 January 2004, at 6:57 a.m.

IDS Forum is maintained by Administrator with WebBBS 5.12.