UnixPedia : HPUX / LINUX / SOLARIS: HPUX : How to remove or release share memory and Semaphore

Tuesday, January 22, 2013

Database got hung , and it is believe that it was not cleanly down. Which left some shared memory and semaphore on the server.

While database start up , it complain of share memory.

To check the shared Memory and semaphore :

% ipcs -a

% ipcs -mab

#-> ipcs -ma|grep -i Kondba

m 177307655 0x00000000 --rw-rw---- Kondba condba Kondba condba 21 1462915072 28073 21739 9:49:24 9:51:06 4:31:53

m 1769491 0x00000000 --rw-rw---- Kondba condba Kondba condba 21 1476395008 28073 21739 9:49:24 9:51:06 4:31:53

m 229397 0x00000000 --rw-rw---- Kondba condba Kondba condba 21 1194823680 28073 21739 9:49:24 9:51:06 4:31:53

m 196630 0x1c9e12b0 --rw-rw---- Kondba condba Kondba condba 21 12288 28073 21739 9:49:24 9:51:06 4:31:53

m 32793 0x00000000 --rw-rw---- Kondba condba Kondba condba 0 507408384 22350 27863 5:41:15 5:41:15 0:44:12

m 32794 0x3d6313d4 --rw-rw---- Kondba condba Kondba condba 0 12288 22350 22298 9:52:23 9:52:23 0:44:12

m 11304987 0x90321bdc --rw-r----- Kondba condba Kondba condba 13 1075056640 29768 21978 9:50:04 9:51:12 1:04:19

m 327708 0xdc600560 --rw-r----- Kondba condba Kondba condba 16 1074008064 305 21291 9:48:09 9:48:09 1:05:20

m 229405 0x3aec7cb8 --rw-r----- Kondba condba Kondba condba 15 897847296 475 21315 9:48:24 9:48:24 1:06:02

Below process have NATTACH value is equal to 0

32793 0x00000000 --rw-rw---- Kondba condba Kondba condba 0

32794 0x3d6313d4 --rw-rw---- Kondba condba Kondba condba 0
One line command to check the NATTACH :

#ipcs -mob |awk '$1=="m" && $7==0 {print $0}'

The command syntax to remove the shared memory segments or semaphores is as follows:

% ipcrm -m <shared memory id>

% ipcrm -s <semaphore id>

% ipcrm -m 32793

% ipcrm -m 32794

After cleaning the shared memory , DB will be started successfully.

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