I am using Windows Server 2008 Enterprise. I heard it is better to store page file on the same disk as OS (normally disk C), is that correct? If so, any document about this point?
thanks in advance, George
The best place to store the paging file is on a volume that allows for fast, random access. If your server's workload is such that there's not a lot of random IO occurring on the volume where the OS is located then putting the pagefile there is fine. Ideally, you'll have enough physical RAM that you're not paging a lot so it won't matter than much anyway.
If you're planning a workload that will involve any quantity of paging and random IO on the OS volume then you might want to consider a paging volume on a dedicated spindle.
In several documents re: application performance improvement Microsoft makes statements re: putting the pagefile on a dedicated volume. In Operating System Optimizations for BizTalk Server, just as an example, they state:
Isolate the paging file onto one or more dedicated physical drives that are configured as either RAID-0 (striping) or RAID-1 (mirroring) arrays, or on single disks without RAID - By using a dedicated disk or drive array where PAGEFILE.SYS is the only file on the entire volume, the paging file will not become fragmented, which will also improve performance.
You'll find statements like that in documents relating to SQL Server, Exchange, and general OS performance. The pagefile, assuming paging is occurring, is a sink for random IO capacity.
Be warned, though, that if you don't have a pagefile on the OS volume at least the size of physical memory + 1MB the OS won't be able to write complete physical memory dumps in the event of a crash. If full memory dumps aren't important to you then you can get away with a smaller pagefile on the OS volume. Small memory dumps can be written into smaller page files, though. See KB254649 for details and for information about the "rules" in Windows Vista, Server 2008, and 7.