Excessive Paging in Window Server 2003 64 bit

Question

All,

Thanks in advance for your help.

I need to understand how to get a handle on what I consider is excessive paging on one of my servers.

The server is a 16 processor 64-bit Windows Server 2003 - datacenter version. we run SQL Server 2005 enterprise. It also runs an application from i2 called Demand Planner.

The paging spikes throughout the day usually to between 6,000 and 10,000 pages per second.

I monitor the memory using Idera's Diagnostic Manager and can see that when the high paging is happening the total memory is under 60GB. I have SQL Set to a max memory of 50GB leaving 14GB for OS and other processes. the i2 demand planner app is a 32bit app so it should not be using more then about 2gb.

What should I be looking at to determine the cause of this paging, and how should i get it under control.

Thanks, Richard

Answer 1

The "Page Faults / sec" counter for each instance under the "Process" object (i.e. each process running on the box) is going to tell you which processes are creating the page faults. You can see the page faults with "Task Manager" by turning on the "Page Faults Delta" column, as well.

The problem with "Page Faults / sec" is that it includes both hard and soft (that is, page faults where the page needed is still in physical memory) faults. Soft faults aren't expensive.

You really want to see whether you're having a significant number of hard page faults (that is, page faults that have to go to the disk) or not. Watch the "Pages Input / sec" counter in the "Memory" object to get a feel for how many hard page faults are occurring.

Hard page faults occur when the memory page needed to fulfill the request must be read from disk. The "fix" for hard page faults is to add physical RAM.

Soft page faults occur when an application first writes to a new page (copy on write), asks for a page to be zeroed, or accesses a page that's already elsewhere in memory (like a memory-mapped file being used by another process). You probably can't do a lot to "fix" it if you're seeing a lot of soft page faults, but you shouldn't be too worried about them either.