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[LDM #NNE-789939]: Quick question: what is ipcs trying to tell me here?

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  • Subject: [LDM #NNE-789939]: Quick question: what is ipcs trying to tell me here?
  • Date: Wed, 18 Jul 2007 12:31:34 -0600
Hi Gilbert,

re: origin of shared memory segments listed with 'ipcs'

> That's what I thought, but I just wanted to make sure. Thanks!

Actually, a number of the shared memory segments are from the McIDAS-XCD
decoders that are running on your machine.  Like Steve said, these can
safely be ignored most of the time.  The times they can not be ignored
is if something runs amok and you end up with lots and lots of shared
memory segments.  If this ever happens, then I recommend that you do
the following:

<as 'ldm'>
ldmadmin stop       <- important that you stop the LDM before continuing!

ipcs                <- if the output from 'ipcs' shows a number of shared
                       memory segments used for McIDAS, you will need to
                       remove them.

The shared memory segments used by McIDAS will be one of two sizes.  In your
listing:

------ Shared Memory Segments --------
key shmid owner perms bytes nattch status
0x00000000 196608 ldm 600 384320 0
0x00000000 229377 ldm 600 512000 0
0x00000000 294914 ldm 600 384320 0
0x00000000 327683 ldm 600 512000 0
0x00000000 360452 ldm 600 393216 2 dest
0x00000000 393221 ldm 600 393216 2 dest
0x00000000 425990 ldm 600 393216 2 dest
0x00000000 458759 ldm 600 393216 2 dest
0x00000000 491528 ldm 600 393216 2 dest
0x00000000 524297 ldm 600 393216 2 dest
0x00000000 557066 ldm 600 393216 2 dest
0x00000000 589835 ldm 600 12288 2 dest
0x00000000 622604 ldm 600 12288 2 dest
key semid owner perms nsems
0x00000000 491520 apache 600 1
0x00000000 32769 apache 600 1
0x00000000 524290 apache 600 1
0x00000000 557059 apache 600 1
0x00000000 589828 apache 600 1
0x00000000 622597 apache 600 1
0x00000000 655366 apache 600 1
0x00000000 688135 apache 600 1

------ Message Queues --------
key msqid owner perms used-bytes messages

the shared memory segments used by McIDAS processes are the
ones of size 384320 or 512000.

You remove shared memory segments using 'ipcrm'.  For instance
(again, only do this when the LDM is stopped):

ipcrm -m 196608
ipcrm -m 229377
 etc.

Tbe other way to remove unwanted/unused shared memory segments is to
reboot.

After deleting all of the shared memory segments that were created
by McIDAS processes (NB: they may all be gone after stopping the LDM),
do the following:

<still as 'ldm'>
cd ~ldm/.mctmp
rm -rf *            <- make sure you are in ~ldm/.mctmp before running this!!

Voila!

Cheers,

Tom
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Ticket Details
===================
Ticket ID: NNE-789939
Department: Support LDM
Priority: Normal
Status: Closed