Oracle sysresv utility to release shared memory / semaphores -- No need for ipcs and ipcrm

After shutdown of Oracle database , shared memory segments staying behind is known issues   in Linux .  Ideally Dba use Ipcs and Ipcrm  to release  shared  memory segments .

Also there is less known Linux utility pmap 

Eg :  [oracle]$ pmap `pgrep -f lgwr`

There is  Oracle utility sysresv  that can  be used to release shared memory segments and there is no need  to use Ipcs and Ipcrm .  

Eg :  sysresv -l instance1 

 

Usage:

------

sysresv: 

usage   : sysresv [-if] [-d <on/off>] [-l sid1 <sid2> ...]

          -i : Prompt before removing ipc resources for each sid

          -f : Remove ipc resources silently, oevrrides -i option

          -d <on/off> : List ipc resources for each sid if on

          -l sid1 <sid2> .. : apply sysresv to each sid

Default : sysresv -d on -l $ORACLE_SID

Note    : ipc resources are attempted to be deleted for a

          sid only if there is no currently running instance

          with that sid. 

   
Examples:
---------

o  Instance is not running:

   /u02/app/oracle/product/8.1.7> sysresv

   IPC Resources for ORACLE_SID "R817" :
   Shared Memory
   ID              KEY
   No shared memory segments used
   Semaphores:
   ID              KEY
   No semaphore resources used
   Oracle Instance not alive for sid "R817" 


o  Instance is running:

   /u03/app/oracle/product/8.1.6> sysresv

   IPC Resources for ORACLE_SID "ORCL" :
   Shared Memory:
   ID              KEY
   16437           0xe4efa8dc
   Semaphores:
   ID              KEY
   12320802        0x09d48346
   Oracle Instance alive for sid "ORCL"


o  Attempting to remove memory and semphores using sysresv when Oracle 
   detects an instance is running:

   /u03/app/oracle/product/8.1.6> sysresv -f

   IPC Resources for ORACLE_SID "ORCL" :
   Shared Memory:
   ID              KEY
   16437           0xe4efa8dc
   Semaphores:
   ID              KEY
   12320802        0x09d48346
   Oracle Instance alive for sid "ORCL"
   SYSRESV-005: Warning
           Instance maybe alive - aborting remove for sid "ORCL" 


o  Removing IPC resources:

   [Sysresv shows memory and semaphores exist but Oracle determines the 
    instance is not alive.  Cleanup is needed.]

   /u03/app/oracle/product/8.1.6> sysresv

   IPC Resources for ORACLE_SID "ORCL" :
   Shared Memory:
   ID              KEY
   16837           0xe4efa8dc
   Semaphores:
   ID              KEY
   12714018        0x09d48346
   Oracle Instance not alive for sid "ORCL" 
 

o  Removing IPC resources using sysresv:

   /u03/app/oracle/product/8.1.6> sysresv -i

   IPC Resources for ORACLE_SID "ORCL" :
   Shared Memory
   ID              KEY
   No shared memory segments used
   Semaphores:
   ID              KEY
   No semaphore resources used
   Oracle Instance not alive for sid "ORCL"
   Remove ipc resources for sid "ORCL" (y/n)?y
   Done removing ipc resources for sid "ORCL"
   /u03/app/oracle/product/8.1.6


   Verify the resources were removed:

   /u03/app/oracle/product/8.1.6> sysresv

   IPC Resources for ORACLE_SID "ORCL" :
   Shared Memory
   ID              KEY
   No shared memory segments used
   Semaphores:
   ID              KEY
   No semaphore resources used
   Oracle Instance not alive for sid "ORCL"  

     
o  If you need to remove memory segments, and Oracle detects the
   instance is alive through sysresv:

   % ipcrm -m <memid>

   Where <memid> is the memory id shown in the sysresv output.

   Example:
   % ipcrm -m 16437

   If you need to remove semaphores, and Oracle detects the
   instance is alive through sysresv:

   % ipcrm -s <semid>

   where <semid> is the semaphore id shown in the sysresv output.

   Example:
   % ipcrm -s 12320802

Reference :

SYSRESV Utility (Doc ID 123322.1)

Startup fail with ORA-29701 & ORA-29702 after the DB crash. (Doc ID 2160481.1)