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Shared memory shortage but lots of unused memory


 
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# 1  
Shared memory shortage but lots of unused memory

I am running HP-UX B.11.11.


I'm increasing a parameter for a database engine so that it uses more memory to buffer the disk drive (to speed up performance). I have over 5GB of memory not being used.

But when I try to start the DB with the increased buffer parameter I get told.

"Not enough Shared Memory"

I am told that there is a Kernel paramater that I need to adjust so that I can use that "unused" memory for this DBs startup.

Does anyone know the kernel parameter that will allow me to use more of my available memory as shared memory?

Chris.
# 2  
I can't help you with the specific kernel parameter since I don't know HPUX very well. You'll have to ask your DBA or look it up.

But, I think I know what is going on. Oracle sets its shared memory area when it starts up. Even if it looks to the OS like there is 5GB free, if you take any of it which Oracle expected to be able to use Oracle will complain. If you are setting aside some memory for caching as you described, you probably have to decrease the shared global area in Oracle to compensate.

Hope that helped, I know it wasn't long on details . . .

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