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Value of SHMMAX

Recently the value of SHMMAX was reduced to 8M bytes on our HP-UX 10.20 box, which runs Unidata (now owned by IBM!) After this, GlancePlus fails to start properly (even in character mode). What is the connection? The RAM is 1+ GB. Should we give a arbitrarily high value for SHMMAX? Is there a likely side effect we need to watch?

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I can't believe that anything will load on the system with SHMMAX set so low. The kernel parameter SHMMAX sets the size of the largest contiguous chunk of memory. The only reason to set it low is if you thought you had a process that is grabbing too large of a chunk of memory. I usually set it large (like 500M bytes in your case), just in case I want to make a large SGA for a database.

If you don't have any databases running on this machine, something in the range of 100M bytes would be appropriate.

This was first published in October 2001

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