[jayantpathak]

Is there any formula to calculate shared memory will setting in /etc/system.
What is connection between semaphore with sybase.
how much value we can set in /etc/system in place of shmmax.

[trvishi]

Originally Posted by jayantpathak

Is there any formula to calculate shared memory will setting in /etc/system.
What is connection between semaphore with sybase.
how much value we can set in /etc/system in place of shmmax.

Semaphore is the actual memory used by the Sybsae instance
Shared Memory is the maximum memory all semaphores can use.

ipcs -m (short display), ipcs -a (full display) show sthis.

Ideally if its a box which is only used by Sybase, you can set it to the max possible leaving some for the O/S ofcourse.

prtconf | grep Mem - will show you the memory currently available.

Leave 20% for O/S and allocate the rest for shmmax.

[jayantpathak]

Thanks,
As per my understanding semaphore is a locking mechanism.
When i start the server it will create one instance and that instance is taking some amount of memory to run and semaphore is setting a lock on that part of shared memory.

As per above mail, If my shared memory is 10Gb and i start the server it took 7Gb memory to start that time it will create one sybase instance. At this time what will be the semaphore values.

Kindly help me.