topic Re: Extended file cache size in Operating System - OpenVMS

Extended file cache size

Jeff Wolfe_1 — Tue, 16 Dec 2003 11:09:28 GMT

When doing a sho mem, I'm seeing that 50% of memory is allocated to file cache. (see attached) With only 150K out of 2M pages available on the free list, how do I get some of this memory back? Is VMS manageing this pool of memory? Are there SYSGEN parameters fo manage the pool?

Thanks in advance...

Jeff

Re: Extended file cache size

Craig A Berry — Tue, 16 Dec 2003 11:19:06 GMT

See section 18.5 of the System Manager's manual on controlling the size of the XFC cache. The dynamic system parameter VCC$MAX_CACHE sets the maximum size, but you should really read that section of the manual before deciding if that's what you reall want to do.

Re: Extended file cache size

Martin P.J. Zinser — Tue, 16 Dec 2003 11:22:12 GMT

Hello Jeff,

there should be no need to limit the size as XFC is supposed to give up on memory if it is needed by other processes.

Greetings, Martin

Re: Extended file cache size

Willem Grooters — Wed, 17 Dec 2003 02:59:10 GMT

Jeff
In addition to Martin:

VMS manageing this pool of memory?

definitely YES. So don't worry.
(Am I right that this is just paged memory which will be freed when required? Then 'file cache' is to be considered an ordinary 'user', so it would mean that with a lot of users, the cache will shrink.)

Are there SYSGEN parameters fo manage the pool?

Follow Craig's suggestion. It will tell you how to with what. But I would suggest to let VMS take care unless you know exactly what you do. You may ruin the cache's performance otherwise.

Willem

Re: Extended file cache size

Jeff Wolfe_1 — Wed, 17 Dec 2003 07:32:37 GMT

Thanks for the responses!

Jeff