Re: Pagefile placement

***

That's the first time I have seen Bruce's Article.

I found this part interesting:

"If the minimum and maximum pagefile sizes are not the same, the
pagefile will initially be allocated to the minimum size, then expanded
as more space is needed, up to the maximum. On most systems, this will
mean that the pagefile will be fragmented, possibly in widely separated
parts of the disk. If there is a significant amount of paging activity,
this can lead to unnecessary performance degradation. Setting the
minimum and maximum the same size may still result in a fragmented
pagefile, but does reduce the likelihood of serious fragmentation. If
the system is paging heavily and the pagefile is heavily fragmented,
consider moving the pagefile to a newly formatted partition on a
separate disk."

If the pagefile is in the Windows partition is a non-contiguous pagefile
it will tend to increase the rate of fragmentation of other files
located in the partitition. The point also goes against the commonly
expressed opinion that it's best to let to let Windows manage the
pagefile. My present setting is a min/max 2 gb page file in the Windows
partition but I have used the first partition on a second drive for a
dedicated pagefile partition in the past. The only reason for the change
was that I was having difficulties getting a dual boot set up to work
when I created my latest set up.



~~~~


Gerry
~~~~
FCA
Stourport, England
Enquire, plan and execute
~~~~~~~~~~~~~~~~~~~
*** W. Jonsson wrote:
Hi again!

I feel that I need to add that (in my opinion) it is always best to
have the main bulk of the pagefile on a separate physical drive than
your windows is installed to.. And preferably in a partition of its
own..

And a thought on that "a partition in the beginning of the drive"
talk:
And since your disk has a large cache it does not mater if you have
your pagefile on an partition that is in the beginning of the drive
or not.


Why?
Since a modern harddrive is built up by several physical disks
internally you don't have only one "beginning". You have, in fact,
one "beginning" per read/writable side of each physical disk.. (A
modern harddrive is not a one sided Disk? Is it?)

So if your disk has 2 double sided physical disks internally you will
in fact have 4 "beginnings".. (and 4 arms for reading/writing)

So.. In theory the optimum would be to have 4 equally large
partitions on the above disk, so that all 4 partitions subside on one
side of each "disk" only, and all 4 read/write-arms can write or read
data at the same time? (Right?)

;0)

"*** W. Jonsson" wrote:

Hi!

There seems to be a lot of guessing going around.

I my self has read Bruce Sanderson's excellent article "RAM, Virtual
Memory, PageFile and all that stuff" ( at:
http://members.shaw.ca/bsanders/WindowsGeneralWeb/RAMVirtualMemoryPageFileEtc.htm
)

and in section 1.3 it clearly says "the operating system will move
pages (4
KB pieces) of one or more virtual address spaces to the computer's
hard disk"

Now Please note that it´s 4KB pieces that is moved. It is important
to my
next question/statement..

Does not Harddrives as of today have a relatively large "Cache"???

So. It your operative system is moving stuff to your swap-file in
4KB pieces
at the time..

Does not your harddrive store these 4KB pieces in it's cache BEFORE
it is
written to the physical drive??

And if so.. Does not that procedure equal out all the sk. unnecessary
movements of the read/write arms? (It will store a bunch of 4KB
pieces and
write several at the time to the physical disk)

In short:
People who discuss page files and it's placement seems to forget the
4KB
piece bit and the diskcache bit! 2 Things that makes a great
difference in
real life..

So! in my mind it is not a bad idea to put the pagefile on a separate
partition on the same physical disk, considering above!
Especially when you get much less fragmentation on your windows
partition.. Especially when your pagefile will not get fragmented.

Does anyone agree??

(Please excuse my English, I Swedish so English is not my native
"mode" ;0)


"Ken Blake, MVP" wrote:

On Wed, 13 Aug 2008 10:38:02 -0700, MrMako
<MrMako@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote:

A little debate is going on here at work as too the best placement
of the pagefile on a Windows Xp system. Boss is looking for MS
best Practice, which I read as move it to a different partition.
He currently has the desktop group apply this by creating a D:
drive on the same partition and placing it there.

Our argument is over whether this actually provides any
performance boots over having it on the C: drive with the boot and
system partition. Some of us think it is the same either way and
you have to move it to another DRIVE to get any actual performance
boost, but others insists the second partition on same drive works.


Yes, it works. But it is *not* a good idea. Not only will it not
provide a performance boost, it may actually provide a performance
degradation.

What doing this does is move the page file to a location on the hard
drive distant from the other frequently-used data on the drive. The
result is that every time Windows needs to use the page file, the
time to get to it and back from it is increased.

Putting the page file on a second *physical* drive is a good idea,
since it decreases head movement, but not to a second partition on a
single drive. A good rule of thumb is that the page file should be
on the most-used partition of the least-used physical drive. For
almost everyone with a single drive, that's C:.

If you have enough RAM, the penalty for moving the page file to a
second partition may be slight, since you won't use the page file
much, but it will never help you.

--
Ken Blake, Microsoft MVP - Windows Desktop Experience
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