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semaphores and shared memory

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Special Forums Hardware Filesystems, Disks and Memory semaphores and shared memory
# 1  
Old 06-08-2002
Question semaphores and shared memory
hello,
Can any one please answer these 2 questions?

1. What is the purpose of SEMAPHORES and SHARED MEMORY on a Unix platform?

2. What would require a SYS. ADMIN to set SEMAPHORES and SHARED MEMORY on a Unix platform?

Thanks,
Ted
# 2  
Old 06-08-2002
These are two types IPC facilities. IPC (Inter Process Communication) allows two or more processes to talk with one another. They both require space in kernel tables if they are to be successfully allocated. That's where the SysAdmin comes in. He or she must ensure that there is room for all the IPC's that the system needs.

One example is a relational database management system such as Oracle or Sybase. A RDBMS might have one server program that actually talks to the disk drives. And it would have multiple client programs that need to use the database. The programs communicate via IPC's. And when you install Oracle or Sybase, one of the steps is to review the kernel IPC parameters. They usually will need to be increased.
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