I have the onstat -a of our the Informix Instance at the time of our
database was crashing. See below the error message we where getting
during the time of crash:-

11:36:07 shmget: [EEXIST][17]: key 52564803: shared memory already
exists
11:36:07 create_tcb: cannot allocate memory

We are running our Application in Dell 6600 Server with 4 CPU, 4GB RAM
and data speard over 12 Disks. Our Informix Version is 9.3 .

I would apprericate if anybody could help me in analysis the onstat-a
output and recommending changes to our parameter. ( Basic issue is
performance).

Please e-mail me so I can forward the onstat-a output.

Thanks in advance..

Dhaya

dhaya.snidhi@gmail.com wrote:
> I have the onstat -a of our the Informix Instance at the time of our
> database was crashing. See below the error message we where getting
> during the time of crash:-
>
> 11:36:07 shmget: [EEXIST][17]: key 52564803: shared memory already
^^^^^^^^^^^^^^^^^^^^
This is the 'key' if you'll pardon the pun. IDS creates several shared
memory segments using keys that are calculated off a base value (0x52564800)
plus 0x00010000 time the SERVERNUM (in your case zero) plus the segment
number. So the first segment for your server (the RESIDENT segment) would
be keyed as 0x52564801 and the key 52564803 is the third segment or second
virtual segment. Apparently either this key clashes with another
application's use of shared memory key values or there was an old segment
left in memory the server crashed or was taken down previously. Use ipcs to
determine the owner of the segment. If it is an IDS segment it will be
owned by root or informix (version dependent) and group informix. If not,
you can change the SERVERNUM in the ONCONFIG file to change the key range
IDS uses so it no longer clashes with your other apps. If it IS an IDS
segment left over, first try running 'onmode -ky'. This will usually remove
old shared memory segments and semaphore groups. Otherwise use ipcrm to
kill the segments manually.

Art S. Kagel


> exists
> 11:36:07 create_tcb: cannot allocate memory
>
> We are running our Application in Dell 6600 Server with 4 CPU, 4GB RAM
> and data speard over 12 Disks. Our Informix Version is 9.3 .
>
> I would apprericate if anybody could help me in analysis the onstat-a
> output and recommending changes to our parameter. ( Basic issue is
> performance).
>
> Please e-mail me so I can forward the onstat-a output.
>
> Thanks in advance..
>
> Dhaya
>