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Entry  11 Apr 2013, Thorsten Lux, Forum, Persistent ipcrm error 
    Reply  11 Apr 2013, Konstantin Olchanski, Forum, Persistent ipcrm error 
    Reply  11 Apr 2013, Stefan Ritt, Forum, Persistent ipcrm error 
       Reply  12 Apr 2013, Thorsten Lux, Forum, Persistent ipcrm error 
          Reply  12 Apr 2013, Stefan Ritt, Forum, Persistent ipcrm error 
             Reply  12 Apr 2013, Thorsten Lux, Forum, Persistent ipcrm error 
    Reply  12 Apr 2013, Thorsten Lux, Forum, Persistent ipcrm error 
       Reply  12 Apr 2013, Stefan Ritt, Forum, Persistent ipcrm error 
Message ID: 873     Entry time: 11 Apr 2013     Reply to this: 874   875   879
Author: Thorsten Lux 
Topic: Forum 
Subject: Persistent ipcrm error 
Hello,

I have a problem with our DAQ which is based on Midas. Until now, for about 3 years, it worked quite well but since I tried to restart data taking after a break of 2 months, I get always the following error message:

[system.c:308:ss_shm_open,ERROR] Shared memory segment with key 0x4d008002 already exists, please remove it manually: ipcrm -M 0x4d008002
[midas.c:1950:cm_connect_experiment1,ERROR] cannot open database
Unexpected error #304

Then I tried the following to fix the problem:

-) I first checked with ipcs the shared memory segments:
0x4d008002 3244040 next 666 1077248 1
0x4d00006e 3276809 next 666 116444 1

Sometimes there is an additional line which I also delete.

-) I deleted with ipcrm -M 0x4d008002 / 0x4d00006e the shared memory segments

-) I removed the .SYS*.SHM files:
-rw-r--r-- 1 next users 0 Mar 16 2010 MIDAS/online/.ALARM.SHM
-rw-r--r-- 1 next users 0 Mar 16 2010 MIDAS/online/.ELOG.SHM
-rw-r--r-- 1 next users 0 Mar 16 2010 MIDAS/online/.HISTORY.SHM
-rw-r--r-- 1 next users 0 Mar 16 2010 MIDAS/online/.MSG.SHM
-rw-r--r-- 1 next users 1089536 Apr 11 15:46 MIDAS/online/.ODB.SHM
-rw-r--r-- 1 next users 116444 Apr 11 15:43 MIDAS/online/.SYSMSG.SHM
-rw-r--r-- 1 next users 16793660 Apr 11 15:43 MIDAS/online/.SYSTEM.SHM

-) I reboot the PC

-) I start the midas daemon using a shell script with the following lines:
cd /home/next/CAEN/A2818Drv/
sudo sh a2818_load
mhttpd -p 8080 -D

-) Normally I can start then a run but when I try to stop it I get again the error message from above.

In addition I get from time to time the following error messages:
[mhttpd,INFO] Client 'unknown' on buffer 'SYSMSG' removed by cm_watchdog because client pid 3287 does not exist
[NEXT DAQ,INFO] Client 'unknown' on buffer 'SYSMSG' removed by bm_wait_for_free_space because client pid 3280 does not exist
[mtransition,INFO] Client 'mhttpd' (PID 3229) on buffer 'ODB' removed by cm_watchdog (idle 47.4s,TO 10s)


Since all this did not help and although there was no update of the operation system, I decided the recompile the whole midas framework on this machine.
It compiled and I installed but the error persisted. In addition now I cannot start anymore the mlogger from the web interface but only manually. However, I can stop it from the web interface.

Do you have an idea what could be the problem? I start to be a bit desperate. Also because I am user of the DAQ system but the person who developed the system in the past, left already some years ago.

I am using a midas version from the 15.03.2010 (midas20100315.tar.gz) as it seems. In principle there is only one frontend device, a CAEN V1740 digitizer, connected to Midas.

Thanks!
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