Oracle
Utilities and Tools
SYSRESV
exclusive for UNIX systems
Doc
Id: Note: 123322.1 On Meatlink
Purpose:
========
The purpose of this bulletin is to introduce a new utility, "sysresv",
provided in Oracle 8.1.5 and above.
Scope & Application:
====================
This bulletin is intended for database administrators and system administrators.
Examples of using the sysresv utility are provided below.
SYSRESV Utility:
================
This utility was the result of enhancement request 566223 [BUG: 566223]:
"Currently, many Oracle applications determine whether a particular
instance is up by checking for the presence of the sgadef file. We should
provide a separate utility for this purpose instead, based on the contents
of the SGA."
The sysresv utility included with Oracle 8.1.5 and above provides instance
status (and OS resources used) for specified ORACLE_SIDs. This utility
is especially useful when multiple instances are running. OS resources
can be removed using this utility if the specified instance is detected
to be dead.
This utility may be useful when an instance has crashed or was aborted
and memory and semaphores related to this instance were not cleaned up
automatically. This utility is also helpful in determining which instance
is running. The sysresv utility, located in $O_H/bin, can be used from
locations other than $O_H/bin.
Point your environment to the instance of interest before using sysresv.
NOTE: (9i 64-bit):
Must set up as follows to get sysresv to work.
Oracle 9.X.X (64Bit) on Solaris (64Bit) OS
- Set LD_LIBRARY_PATH=$ORACLE_HOME/lib32
- Set LD_LIBRARY_PATH_64=$ORACLE_HOME/lib
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, over rides -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:
---------
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"
Instance is running:
/u03/app/oracle/product/8.1.6> sysresv
IPC Resources for ORACLE_SID "X816" :
Shared Memory:
ID KEY
16437 0xe4efa8dc
Semaphores:
ID KEY
12320802 0x09d48346
Oracle Instance alive for sid "X816"
Attempting to remove memory and semaphores using sysresv when Oracle detects
an instance is running:
/u03/app/oracle/product/8.1.6> sysresv -f
IPC Resources for ORACLE_SID "X816" :
Shared Memory:
ID KEY
16437 0xe4efa8dc
Semaphores:
ID KEY
12320802 0x09d48346
Oracle Instance alive for sid "X816"
SYSRESV-005: Warning
Instance maybe alive - aborting remove for sid "X816"
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 "X816" :
Shared Memory:
ID KEY
16837 0xe4efa8dc
Semaphores:
ID KEY
12714018 0x09d48346
Oracle Instance not alive for sid "X816"
Removing IPC resources using sysresv:
/u03/app/oracle/product/8.1.6> sysresv -i
IPC Resources for ORACLE_SID "X816" :
Shared Memory
ID KEY
No shared memory segments used
Semaphores:
ID KEY
No semaphore resources used
Oracle
Instance not alive for sid "X816"
Remove ipc resources for sid "X816" (y/n)?y
Done removing ipc resources for sid "X816"
/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 "X816" :
Shared Memory
ID KEY
No shared memory segments used
Semaphores:
ID KEY
No semaphore resources used
Oracle Instance not alive for sid "X816"
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
115235.1
Resolving ORA-7279 or ORA-27146 errors when starting instance
Problem
Description
-------------------
When attempting to start an instance, you receive the following error:
ORA-7279: spcre: semget error, unable to get first semaphore set
This error may possibly be accompanied by one or more of the following
additional errors:
ORA-600: internal error code, arguments [SKGMBUSY]
SVR4 error: 28: no space left on device
If you are using version 8.1.5 or 8.1.6, you receive the following error
instead of the ora-7279 when attempting to start an instance:
ORA-27146: post/wait initialization failed
With 8.1.7, instance startup fails with ora-3113.
These errors happen whenever attempting to start an instance, which includes,
but is not limited to, creating a new database during an install, creating
a new database with an existing install, starting an existing database
which had the initSID.ora parameter PROCESSES changed, or starting an
existing database which was either shutdown incorrectly or crashed.
Solution Description
--------------------
The problem is that there are not enough semaphores to start the instance.
This can be resolved based on one of the two scenarios below:
Scenario
1
----------
If no new instances have been created and you are trying to start an existing
database which was shutdown incorrectly or crashed, the semaphores from
the crashed instance may still be allocated and will need to be removed.
Step 1)
Before
removing semaphores, you should be certain that there are no running instances
using them. First check for running instances using the following command:
% ps -ef | grep -v grep | grep pmon
If there are no pmon processes running, then there should be no semaphores
owned by the oracle user, and any semaphores owned by the oracle user
can safely be removed.
See
steps 3 and 4 for the commands to list and remove semaphores.
Step
2)
If
you have multiple instances running, you will need to either shut them
down or determine which semaphores are being used by each instance. It
is recommended that you shut down all of the instances, but if this is
not possible, then follow the instructions below.
A) If the running instances are version 8.1.x or higher, set your environment
to that of the running instance, then run the following command:
% $ORACLE_HOME/bin/sysresv
This will show you the semaphore ids being used by this instance. Make
a note of them and repeat the sysresv command for each running instance.
B) If you are not running version 8.1.x or higher, use the following commands
to get a listing of semaphores:
% svrmgrl
svrmgr> connect internal
svrmgr> oradebug ipc
Repeat these commands for each running instance making note of the "Semaphore
identifiers" for each.
Step 3)
Now
get a list of all of the allocated semaphores on the system using the
following command:
% ipcs -sb | grep -v grep | grep <oracle>
where <oracle> is the name of the oracle user.
Compare the output of the ipcs command with the notes you made from the
sysresv command or oradebug ipc command , and remove any semaphores that
do not belong to a running instance.
Step 4)
You can remove semaphores using the following command:
% ipcrm -s <semid>
where <semid> is the semaphore id shown in the second column of
the ipcs output titled ID.
Step 5)
Now try to start your instance again.
Scenario 2
----------
You are trying to start a new instance, or an existing instance that had
the initSID.ora parameter PROCESSES changed. You will need to raise the
kernel parameter SEMMNS.
Set the kernel parameter SEMMNS to double the sum of all of the initSID.ora
PROCESSES parameters on the system.
For example, if you have 5 instances with the initSID.ora PROCESSES parameter
set to 25, 50, 100, 200, and 250, then set the kernel parameter SEMMNS
equal to 1250.
((25 + 50 + 100 + 200 + 250) * 2) = 1250
After making changes to the kernel parameter SEMMNS, you will be required
to reboot the system. Depending on your operating system, you may also
be required to rebuild the kernel. For more information on changing kernel
parameters, please consult your OS documentation and/or your OS vendor.
Explanation
-----------
When an Oracle instance is started, oracle will attempt to allocate all
of the needed semaphores. If it is unable to do so, it will generate either
an ora-7279 or ora-27146 error and will fail to start the instance.
References
----------
Note: 15566.1
Additional Search Words
-----------------------
Database Configuration Assistant DBCA ora-3114
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