Set Kernel Parameters for Linux

Related Topics

• Configure Kernel Parameters - Unix/Macintosh

Before You Begin

• Within the following procedure, the range of prescribed values for each kernel parameter is provided.  Where relevant, enter the value that factors in the desired number of data pipe streams. Be sure to use the formula provided for each affected parameter to calculate its value (i.e., parameter value = 64 * desired number of streams). 
• Ideally, if the system will be configured as an iDataAgent, update each affected parameter value to accommodate 10 streams. If the system will be configured as a MediaAgent, allocate no fewer than 100 additional streams per affected parameter.  In any case, ensure that the parameter value does not exceed the "high-end value" of the range provided for the parameter in question.  Of course, if the system will be configured as both an iDataAgent and a MediaAgent, be sure to consider the sum of the respective parameter values for this purpose.

To set the kernel parameters for Linux

Complete the following steps.

1. Log in to the client as root.
2. Navigate to /proc/sys/kernel.
3. Review the current semaphore parameters in the sem file (by entering cat sem , for example).  The output provides the current value for the following parameters in the order listed:  SEMMSL, SEMMNS, SEMOPM, and SEMMNI.  For example:
   
   250 32000 32 128
   
   In this example, SEMMSL=250, SEMMNS=32000, SEMOPM=32, and SEMMNI=128
    
4. Where required, replace each parameter variable with the appropriate value for the parameter.   Be sure to use the following table to determine a value that falls within the prescribed range of values for the parameter.  If the system will be configured as an iDataAgent, update each affected parameter value to accommodate 10 streams. If the system will be configured as a MediaAgent, allocate no fewer than 100 additional streams per affected parameter.

   If '*" appears after the parameter name, this indicates that you can increment the value of the parameter based on the number of desired streams by using the formula parameter value = 64 * number of desired streams as long as the "high-end" value of the range for the parameter is not exceeded.

   Parameter	Purpose	Possible Range of Values
   SEMMSL*	Defines the minimum recommended semaphore value	1 – 2147483647 [MAXINT]
   SEMMNS*	Defines the maximum semaphores in the system	1 – 2147483647 [MAXINT]
   SEMOPM	Defines the maximum number of operations for each semaphore call	100
   SHMMNI*	Defines the maximum number of shared memory segments in the entire system	1 – 2147483647 [MAXINT]

    

5. Review the current shared memory parameters (e.g., cat shmmax, etc.).
6. Where required, update the value for each shared memory parameter.   Be sure to use the following table to determine a value that falls within the prescribed range of values for the parameter.

   If '*" appears after the parameter name, this indicates that you can increment the value of the parameter based on the number of desired streams by using the formula parameter value = 64 * number of desired streams as long as the "high-end" value of the range for the parameter is not exceeded.

   If a MediaAgent is included, be sure allocate no fewer than 100 additional streams per affected parameter.
    

   Parameter	Purpose	Possible Range of Values
   SHMMAX	Defines the maximum allowable size of one shared memory segment	0 – 2147483648 [2 GB] (the high-end value is the recommended value)
   SHMMNI*	Defines the maximum number of shared memory segments in the entire system	1 – 2147483647 [MAXINT]
   SHMALL	Defines the maximum total shared memory system-wide	2097152

7. For a non-Red Hat Linux system, reboot the system to allow the changes to take effect. For a Red Hat Linux system, edit the /etc/sysctl.conf file if necessary to make the changes permanent as follows:

   kernel.shmmax = value
   kernel.sem = value1 value2 value3 value4

   (Be sure to include a space on either side of each "=" and also between each value.) Then run the sysctl -p command to allow these changes to take effect immediately.