• ab.sqlservercentral (8/18/2010)


    Guys,

    those pagefile discussion drives me crazy. First, most of the posts are off-topic. The discussion is about MEMORY DUMPS, not about paging file calculation. Second, most people don't know the internals about paging:

    - for all those who complained to need "hacks" and "tricks" and want to configure it to a minimum: Windows doesn't need a paging file.

    - for those of you who calculate the paging file based on RAM: This is a wrong approach. The paging file doesn't need to be "2x RAM or 4x RAM" - it just depends. [snip] (and as I told in a previous post: Configure a kernel memory dump, that's enough in 98% of all cases).

    - for those of you who care about fragmentation in the PF: The performance drop WHEN the paging file is used (it won't be often!) is THAT high that fragmentation just doesn't matter.

    - Despite all myths about it: paging doesn't happen often. It's very hard to see (and DON'T take the hard faults as an indicator of paging!). [snip]

    - A thumb rule: monitor your server look how the "peak commit limit" behaves. This is what might get paged out at MAX on your server to the paging file in the worst case. This number should be the basis of your calculation, not the size of RAM.

    - If you use AWE in your SQL Server to support more than , your pages will NEVER be paged out.

    - IF you set "lock pages in memory" your SQL Server pages will not get trimmed in case of high memory demand.

    regards

    Andreas

    +5 Andreas!

    on a small dev/test server, a large pagefile may be necessary, but a production db server shouldn't have a higher peak commit than its accesible physical ram. in fact, a large pagefile can hinder performance because the OS could start swapping executable pages -- that will kill performance. i would never suggest limping along in a memory starved environment by adding more paging space even if its on an ssd