Page file on OS drive (2xRAID) or secondary drive?

NoxTek

NoxTek

The Geek Redneck
Joined
May 27, 2002
Messages
9,300
Quick 'which should be faster' question for you guys...

My main rig has three Western Digital 640GB AAKS drives in it, two of which are in a RAID0 array being used for Windows 7. This leaves a third drive that I use for various storage tasks and video editing duties. My question is would it be better to have Windows keep it's swap file (aka page file) on the RAID0 array which the OS resides on or the third 640GB drive?

Normally when not running a RAID setup for the OS drive it would be a no brainer - I always told Windows to use another drive for the page file instead of the OS drive to improve performance.

I wish there was some way to benchmark for this particular scenario. *shrug*

What do you guys think?
 
You have 8GB of RAM, so where your pagefile is most likely doesn't matter at all because it will probably not be used. Read http://en.wikipedia.org/wiki/Paging to understand what this means.

Dustin

edit: changed wiki link to something more applicable
 
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Page file != virtual memory, it's just a component of the virtual memory subsystem (I repeat this so much I need a macro for it I swear).

Put a static page file on the system partition/drive and put another one on every physical non-RAID drive/partition you've got in the machine, the more (by sheer number, not size) page files you can create on more physical drives the better, if needed.

And as for the page file not being used, it is because Windows is designed to use it, period. How much it uses it is up for grabs, but even with 8GB, the OP could be putting his machine to some serious work and Windows could be paging quite a bit...

"Assumptions are the Mother of all fuck ups..." -- Some bad guy henchman in "Under Siege"

Makes sense to me. :)
 
Computers without pagesfiles are going to severly suffer from memory fragmentation. This may be okay if it gets rebooted every day, but its critical for servers and high-uptime workstations. Without a pagefile, if the MMU runs out of TLB entries or consecutive pages, your applications will just rufse to start even if there are gigabytes left.

I tend to place the pagefile on the fastest (read: most IOPS, least acces time) drive, but Bahamut may have a point in spreading it over multiple drives.
 
Bahamut said:
Put a static page file on the system partition/drive and put another one on every physical non-RAID drive/partition you've got in the machine, the more (by sheer number, not size) page files you can create on more physical drives the better, if needed.
Click to expand...

But does this have any benefit performance-wise? I have always been of the understanding that Windows doesn't simultaneously access page file space spanned across seperate drives, be they logical or physical. Even though you can create a page file on several physical drives Windows doesn't access them in parallel fashion. Although from reading the wikipedia article it's of note that Linux and BSD DO access swap space on multiple physical drives in parallel.

Am I wrong?

EDIT: I've been googling around and the answer to this question seems vague at best. I did find reference in some Oracle documentation pertaining to what they call 'multiplexing' the virtual memory across multiple drives.

http://download.oracle.com/docs/html/B10163_01/tuning.htm#i1007342
 
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Windows will select whatever pagefile is the least busy to queue a page-out request on. And since Windows can dispatch parallel IO operations, those page-outs can run simultaneously.
 
The problem is that while page-outs can be done ahead of time page-ins cannot. And page-ins obviously have to be done from the disk they reside on regardless of pending IO.
 
Xon said:
Windows will select whatever pagefile is the least busy to queue a page-out request on. And since Windows can dispatch parallel IO operations, those page-outs can run simultaneously.
Click to expand...

Yes, that seems to be the case, but often not... due to user upgrade the wrong component...
CPU, Video card, memory, HDDs... where monitoring those are barely use...

What about just add an extra low cost SATA controller so you can have TWO separate buses
so the I/O from paging is not in cue with other HDD

There is significant performance once it implemented... I can open more than 40 (Yes forty!) windows at the same time...(ranging from Chrome, EI, Office, Burn DVD, compress BD to MKV...)

**
 
FireWire2 said:
Yes, that seems to be the case, but often not... due to user upgrade the wrong component...
CPU, Video card, memory, HDDs... where monitoring those are barely use...

What about just add an extra low cost SATA controller so you can have TWO separate buses
so the I/O from paging is not in cue with other HDD

There is significant performance once it implemented... I can open more than 40 (Yes forty!) windows at the same time...(ranging from Chrome, EI, Office, Burn DVD, compress BD to MKV...)

**
Click to expand...


Available SATA ports aren't a problem, my current board has EIGHT SATA2 ports. Fundage for more drives is a problem :D But within a couple of months I plan to grab a couple of 80GB Intel G2s or Crucial C300.
 
omniscence said:
The problem is that while page-outs can be done ahead of time page-ins cannot.
Click to expand...
Technically, superfetch does do page-in's ahead of time :p

And page-ins obviously have to be done from the disk they reside on regardless of pending IO.
Click to expand...
Hence apps hanging when a lot of page-in's are required. The SATA standard is half-duplex and spinning drives generally can only do a single IO at once.

FireWire2 said:
Yes, that seems to be the case, but often not... due to user upgrade the wrong component...
CPU, Video card, memory, HDDs... where monitoring those are barely use...
Click to expand...
This is why an SSD is such a massive upgrade for most people, even the crap SSDs have a dozen channels which can simultaneously service IO requests at very low latency.
 
But unless Windows is doing a considerable amount of paging to disk, no clever placement of pagefiles is going to result in any substantial gain performance wise. The OP has 8GB of RAM, so unless they are doing things that make use of very large amounts of memory. In the case that they do, based on the fact that they have a quality SSD installed, that would be hands down the best place for whatever pagefile is used.

Dustin
 
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