Optimal Virtual Memory for Two Drives in XP at DVinfo.net

Tim Polster · February 2nd, 2009, 08:25 PM

Hello,

I have an OS drive and a Scratch drive in my PC.

What is the best way to setup my virtual memory?

I have heard only have the pagefile on the second drive and I have heard have one on both drives?

Thanks

Bill Koehler · February 2nd, 2009, 11:22 PM

Put the pagefile in its own partition on the second drive.

The whole idea is to eliminate the primary hard drive having to move the heads for both loading apps AND swap virtual memory. Separating the two functions makes for faster, more efficient operation.

Tripp Woelfel · February 3rd, 2009, 06:40 AM

Putting it on the second drive is the ticket, but I'm not sure that putting it in a separate partition is the best idea. Here's why.

You have no real control over where that partition physically resides on disk. If you create a partition for the swap file and then create a partition for your data the swap file partition may not reside anywhere near where the heads spend most of their time. If the swap file lives, for example, on the outside edge of the platter and the data lives near the middle, you run the risk of increased seek and latency delays.

I'll admit that my knowledge is a bit out of date and my recollection of the NTFS file structure is a little fuzzy but you want the swap file and data to be as close to each other as possible to avoid the potential delays listed above.

Perhaps a little research on the NTFS file system might help us both come up with the best answer.

Bill Ravens · February 3rd, 2009, 07:17 AM

My experience is to create a seperate partition at the head of the second hard drive. Evidence that the partition is, in fact, at the outer edge(and therefore the fastest i/o) can be obtained with disk speed i/o measuring software. Make sure the partition you create is just slightly larger than the pagefile, so that page file fragmentation is kept to a minimum. Likewise, keep the data partition well defragmented and as empty as possible to insure that the data is positioned close as possible to the pagefile partition. My assumption is that data represented by the left side of the defrag indicator bar is at the fastest edge of the disk.

Tripp Woelfel · February 3rd, 2009, 06:26 PM

Quote:

Originally Posted by Bill Ravens

My assumption is that data represented by the left side of the defrag indicator bar is at the fastest edge of the disk.

Kinda depends on how the disk manufacturer lays out sectors on disk. It's true that the linear velocity of the outer edge of the platter is faster than the inner tracks but that's not very germain to I/O performance. The density of the data on disk is pretty uniform. Outer tracks will have more data sectors than inner tracks. Performance can be slightly better on the outer tracks because it can read more data before it has to seek. A seek can miss catching the track before the data comes under the head so you loose one rotation. Not much, I admit, but everything adds up.

Since Windows writes files first to the outside of the platter, having the page file in a partition on the outside of the disk does have merit, but only if the disk is relatively empty. If the drive tends to be more full, like 40% to 70%, which is common for me as I get deeper into a project, it's better to have the page file near the middle in the disk. (I'll use that drive for temporary archiving of project components or transcodes, not active files.) That way the farthest it will have to go is about half way across the platter instead of nearly the full surface if the drive is full.

I know years ago there was a lot of interest in solid state for RAM cache. Don't hear a lot about it these days, but I'm out of that biz now. Should be a lot more cost effective now than when we first considered it back in the early days of video on hard disk.

Yes... I'm old.

Tim Polster · February 3rd, 2009, 06:44 PM

Thanks for your replies.

How about system managed or 2.5 times ram?

Tripp Woelfel · February 4th, 2009, 07:39 AM

Quote:

Originally Posted by Tim Polster

How about system managed or 2.5 times ram?

I don't think there's a single or simple answer to this. It depends upon a lot of things.

For example, Adobe have specific recommendations for Premier Pro CS3. However they could adversely effect other applications. This is a complex question and probably requires a deep understanding of Windows memory management to provide valuable answers.

Tim Polster · February 4th, 2009, 08:42 AM

For now, I have set the pagefile only on the second drive and set a fixed size of 4221 of which windows recommended.

February 2nd, 2009, 08:25 PM	#1
Tim Polster Inner Circle Join Date: Dec 2004 Location: Arlington, TX Posts: 2,231	Optimal Virtual Memory for Two Drives in XP Hello, I have an OS drive and a Scratch drive in my PC. What is the best way to setup my virtual memory? I have heard only have the pagefile on the second drive and I have heard have one on both drives? Thanks

February 2nd, 2009, 11:22 PM	#2
Bill Koehler Major Player Join Date: May 2007 Location: Alpharetta, Georgia, USA Posts: 760	Put the pagefile in its own partition on the second drive. The whole idea is to eliminate the primary hard drive having to move the heads for both loading apps AND swap virtual memory. Separating the two functions makes for faster, more efficient operation. Last edited by Bill Koehler; February 2nd, 2009 at 11:23 PM. Reason: typo

February 3rd, 2009, 06:40 AM	#3
Tripp Woelfel Trustee Join Date: Jan 2008 Location: North Conway, NH Posts: 1,745	Putting it on the second drive is the ticket, but I'm not sure that putting it in a separate partition is the best idea. Here's why. You have no real control over where that partition physically resides on disk. If you create a partition for the swap file and then create a partition for your data the swap file partition may not reside anywhere near where the heads spend most of their time. If the swap file lives, for example, on the outside edge of the platter and the data lives near the middle, you run the risk of increased seek and latency delays. I'll admit that my knowledge is a bit out of date and my recollection of the NTFS file structure is a little fuzzy but you want the swap file and data to be as close to each other as possible to avoid the potential delays listed above. Perhaps a little research on the NTFS file system might help us both come up with the best answer.

February 3rd, 2009, 07:17 AM	#4
Bill Ravens Join Date: Nov 2001 Location: santa fe, nm Posts: 3,264 Images: 10	My experience is to create a seperate partition at the head of the second hard drive. Evidence that the partition is, in fact, at the outer edge(and therefore the fastest i/o) can be obtained with disk speed i/o measuring software. Make sure the partition you create is just slightly larger than the pagefile, so that page file fragmentation is kept to a minimum. Likewise, keep the data partition well defragmented and as empty as possible to insure that the data is positioned close as possible to the pagefile partition. My assumption is that data represented by the left side of the defrag indicator bar is at the fastest edge of the disk.

February 3rd, 2009, 06:44 PM	#6
Tim Polster Inner Circle Join Date: Dec 2004 Location: Arlington, TX Posts: 2,231	Thanks for your replies. How about system managed or 2.5 times ram?

February 4th, 2009, 08:42 AM	#8
Tim Polster Inner Circle Join Date: Dec 2004 Location: Arlington, TX Posts: 2,231	For now, I have set the pagefile only on the second drive and set a fixed size of 4221 of which windows recommended.