Making The Most of Virtual Memory

How you handle virtual memory can have a big impact on your computer's performance. Virtual memory uses part of your hard drive, called the "pagefile," as if it were very slow RAM. Chunks of information (each 4 Kb in the Windows default setting), called "pages," are constantly swapped between RAM and the pagefile as new pieces of programs and data are needed and old ones are discarded.

The advantage of virtual memory is that it gives you the equivalent of gigabytes of RAM. The disadvantage is that this fake RAM runs at disk speed, which is a lot slower than real RAM. However, calling something from the pagefile is still much faster than calling each piece of data from the regular parts of the hard disk.

Keep in mind that no matter how much RAM you have, you can't completely disable virtual memory on a Windows machine without seriously compromising performance. Considering the relative costs of RAM and hard disks, it doesn't make any sense to try. In fact, it's usually not a good idea to decrease the default size of your pagefile because performance is likely to suffer.

However, sometimes it makes sense to increase the size of your page file to tune it to your needs. The right-sized page file can improve the performance of your Windows machine considerably, especially on large, memory-intensive applications such as games.

First, make sure you have enough virtual memory. Your pagefile should be at least 1.5 times the size of your RAM and something less than five times the amount of RAM. Anything over five times the amount of RAM will usually be wasted.

Second, put the pagefile in the right place. Since virtual memory is being constantly written and read, fast access time is important.

Next to making sure you have enough virtual memory, this is probably the most important thing you can do to improve the performance of your virtual memory system.

The ideal solution is to have a separate, fast, hard disk for the page file; one that isn't used by the rest of the operating system or commonly used programs. The thing that takes the most time in disk operations is the head moving across the disk to access new information, or seek time. Using a separate disk for the page file minimizes pagefile seek time.

But just in case, keep a small pagefile on your main disk. It doesn't have to be large because the page file usually isn't that large, but it should be quick, especially on random accesses. That way, if something happens to the disk with your main pagefile, your system will still operate effectively and not try to take over your entire disk for a pagefile. At least 2 MB and no more than 50 MB is a good size to keep on your main disk.

On Windows XP and 2000 systems, use NTFS as the file system when you format the drive with the pagefile and don't bother with fault-tolerant storage schemes like RAID 0 or RAID 5. They extract a performance penalty and the pagefile doesn't need the protection. On the other hand, if you have more than one fast disk, the pagefile can benefit from RAID 0 (striping) across disks because it increases performance. However don't try to spread the pagefile across multiple volumes (logical disks) on the same physical disk. That simply slows things down. Remember, even though separate partitions on the same disk appear to be separate drives, they still are a single physical drive and the access time issues still apply.

Actually setting the pagefile and other virtual memory parameters is easy. Right-click on My Computer, select Properties, go to the Advanced tab, select Performance Options and then Settings. Select the Advanced tab again, and then choose Change under Virtual Memory. Now you can see the parameters and their current settings. If you want to change the size of the pagefile, choose custom and type in the new pagefile size in the box in the Initial size or Maximum size boxes.

There you are! It's just that simple. You can improve system performance without spending a dime on new hardware.