IDS Forum

Re: onmode -ky hangs

Posted By: Martin Fuerderer
Date: Monday, 23 October 2006, at 11:07 a.m.

In Response To: Re: onmode -ky hangs (Sebastian, Norma J.)

Hi,

one IDS's SHM segments can consist of several OS SHM segments.
Looking at "onstat -g seg" output gives you the view of IDS.
Use "ipcs-m" (as user root) to see the OS view of SHM things.
It may give you a different picture.

[ If IDS requests from the OS an SHM segment that is too big, it will
not get it from the OS. In that case IDS is smart enough to request
several smaller segments from the OS. Condition for this to work
is that they are mapped consecutivly in the private memory space
of the requesting process (also see earlier e-mail from me on that
mapping part). With the segments then appearing consecutivly in
the oninit processes' private memory space, IDS can treat these
segments as one big segment. Just as if it would have received
one big segment from the OS. And this is what "onstat -g seg" will
show, rather than the many smaller segments that it actually
had to request from the OS. ]

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

Informix URLs list: http://home.arcor.de/mfu1/informix/urls.html

"Sebastian, Norma J." <NormaJean.Sebastian@tellabs.com>
Sent by: ids-bounces@iiug.org
22.10.2006 04:55
Please respond to
ids@iiug.org

To
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Subject
Re: onmode -ky hangs [7659]

Hello Frank,

You are on IDS 10.00.UC5 (32 bit)
Your onstat -g seg showed :

IBM Informix Dynamic Server Version 10.00.UC5 -- On-Line (CKPT REQ)
-- Up 2 days 21:04:56 -- 2008880 Kbytes
Segment Summary:

id key addr size ovhd class
blkused blkfree
7340036 1382041603 30000000 540672 672 M 132 0
9437187 1382041601 40000000 1708425216 269028 R* 417091 5
9437189 1382041602 b0000000 314572800 10248 V 73279 3521

6 1382041604 e0000000 33554432 1672 V 6482 1710

Total: - - 2,057,093,120 - -
496984 5236

I don't know much about AIX other than hearing an Informix DBA say
something about a limit of 11 memory segments which isn't your problem
as shown above you have 4.

Back when we ran 32 bit IDS on 32 bit Solaris, IDS would crash when it
hit the max memory allowed for 32bit app on 32bit o/s. We upgraded to
64bit.

Check this out:

http://publib16.boulder.ibm.com/pseries/en_US/aixprggd/genprogc/ipc_limi
ts.htm

some info from this link:

The limit that is the most confusing is the maximum number of shared
memory segments that can be attached simultaneously per process. For
64-bit processes, the maximum number of shared memory segments is
268435456. For 32-bit processes, the maximum number of shared memory
segments is 11, unless the extended shmat capability is used. For more
information on extending shmat, see Understanding Memory Mapping.
..........
The following tables summarize the shared memory limits on IPC
mechanisms.
Shared Memory 4.3.0 4.3.1 4.3.2 5.1 5.2
Maximum segment size (32-bit) 256 MB 2 GB 2 GB 2 GB 2 GB
Maximum segment size (64-bit) 256 MB 2 GB 2 GB 64 GB 1 TB
Minimum segment size 1 1 1 1 1
Maximum number of shared memory IDs 4096 4096 131072 131072
131072
Maximum number of segments per process (32-bit) 11 11 11
11 11

Good luck,
Norma Jean

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Messages In This Thread

• onmode -ky hangs
  FRANK -- Monday, 16 October 2006, at 10:38 a.m.
  • RE: onmode -ky hangs
    Julio Gerardo Flores Olvera -- Monday, 16 October 2006, at 11:08 a.m.
  • Re: onmode -ky hangs
    Mark Jamison -- Monday, 16 October 2006, at 11:11 a.m.
    • Re: onmode -ky hangs
      FRANK -- Monday, 16 October 2006, at 11:34 a.m.
      • Re: onmode -ky hangs
        FRANK -- Monday, 16 October 2006, at 5:07 p.m.
        • Re: onmode -ky hangs
          SANJIT CHAKRABORTY -- Wednesday, 18 October 2006, at 11:33 p.m.
          • Re: onmode -ky hangs
            FRANK -- Thursday, 19 October 2006, at 12:26 p.m.
          • Re: onmode -ky hangs
            Jonathan Leffler -- Tuesday, 24 October 2006, at 10:11 a.m.
        • Re: onmode -ky hangs
          Sebastian, Norma J. -- Saturday, 21 October 2006, at 10:55 p.m.
          • Re: onmode -ky hangs
            Martin Fuerderer -- Monday, 23 October 2006, at 11:07 a.m.
  • RE: onmode -ky hangs
    dharmendra sharma -- Monday, 16 October 2006, at 8:22 p.m.

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