IDS Forum

Re: problem during the compilation for ids 7.31UD1 running on linux

Posted By: Tilman Model-Bosch
Date: Thursday, 29 April 2004, at 6:15 a.m.

In Response To: problem during the compilation for ids 7.31UD1 running on linux (James Lim)

Dear Jim,

SHMVIRTSIZE should be set to a value that is a bit higher than the amount
of used
memory during 'normal' operations.
To determine this amount :
- When the system has been running for a while with normal load run the
command 'onstat -g seg'
and search for all segments of class 'V' (for virtual)
- add up all the values in column blkused mulitply the result with the
block size.
The block size is either 4096 or 8192 bytes , depending on you IDS
version.
As far as I know it is 8192 for 7.31.UD1 .
This is the virtual memory currently in use by IDS in Bytes .
# To verify the block size : (<blkused>+ <blkfree>) * <block size> =
<size_of_shm_segment>
- Set SHMVIRTSIZE to an amount a bit larger (maybe 20%) than that value.
! The value in $ONCONFIG is in KB, the above calculation returns # of
bytes.

- Generally SHMVIRTSIZE should be set to a value , that normally dynamic
allocation of additional
SHM segments does not take place.

- SHMADD should be set to a reasonable high value , to avoid the allocation
of many small
SHM segments in case the server has to allocate more SHM segments! 8192
is definitely very low.
On the other hand if it is set very high , this may result in the
allocation of an unnecessary high
amount of memory.


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

Example from a 7.31.UC7 on SOLARIS:

13% onstat -g seg

Informix Dynamic Server Version 7.31.UC7XA8 -- On-Line -- Up 00:00:24 --
917504 Kbytes

Segment Summary:
id key addr size ovhd class blkused blkfree
1075 1381386241 a000000 872415232 14188 R* 105530 966
1076 1381386242 3e000000 67108864 1628 V 7293 899
1077 1381386243 42000000 622592 616 M 68 8
Total: - - 940146688 - - 112891 1873

(* segment locked in memory)

ONCONFIG:
------------------
SHMVIRTSIZE 65536 #in KB
SHMADD 65536 #in KB

There is only one virtual segment here. Size is

blkused blkfree
(7293 + 899) * 8192 = 67108864

Which indeed is the size displayed by onstat, so we verified that 8192 is
the block size!

In this case SHMVIRTSZE seems to be reasonable, as there is still some free
space available ,
while it is not oversized on the other hand.
-------------------------------------------------------------------------------------------------------------

The crash seems to be a consequence of an OS error.

With kind regards
Tilman



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




forum.subscriber@iiug.org wrote on 04/29/2004 02:17:02 AM:

> Happy Day,
>
> I have a problem during the compilation for my object code. during the
> compilation it was running half-way then it stop in my online.log file
> it showing the error as below:
>
> 07:48:15 Dynamically allocated new virtual shared memory segment (size
> 8192KB)
>
> 07:48:15 Dynamically allocated new virtual shared memory segment (size
> 8192KB)
>
> 07:48:15 Dynamically allocated new virtual shared memory segment (size
> 8192KB)
>
> 07:48:15 Dynamically allocated new virtual shared memory segment (size
> 8192KB)
>
> 07:48:15 Dynamically allocated new virtual shared memory segment (size
> 8192KB)
>
> 07:48:15 Dynamically allocated new virtual shared memory segment (size
> 8192KB)
>
> 07:48:15 shmat: [22]: operating system error
> 07:48:15 Assert Failed: errors occurred during mt_notifyvp
> 07:48:15 Informix Dynamic Server Version 7.31.UD1
> 07:48:15 Who: Session(269, informix@linuxsvr3.rhs.net, 28615,
> 401815616)
> Thread(299, sqlexec, 17f0f4d0, 1)
> File: mt.c Line: 9518
> 07:48:19 See Also: /tmp/af.51342be
> 07:48:19 mt.c, line 9518, thread 299, proc id 20703, errors occurred
> during mt_
> notifyvp.
> 07:48:19 PANIC: Attempting to bring system down
>
> p/s: May i know due to what problem is't ? I have a 4 GB of memory swap
> also 4 GB and 2 CPU.
>
> in my onconfig file I set the SHMVIRTSIZE 100000 and SHMADD 8192.
> anything that i need to modifty in my onconfig file ? please advice
>
> Thanks
> Best Regards,
> LIM
>
>
>

Messages In This Thread

• problem during the compilation for ids 7.31UD1 running on linux
  James Lim -- Wednesday, 28 April 2004, at 8:17 p.m.
  • Re: problem during the compilation for ids 7.31UD1 running on linux
    Tilman Model-Bosch -- Thursday, 29 April 2004, at 6:15 a.m.

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