Location of system and cache partitions

[Old Guy]

My Windows XP defaults to 1536 MB with 1 GB of RAM. I don't know what
it depends on.

Yeah, that's the right default. I couldn't remember is it was 150% or
200% of memory size.

 

[Old Guy]

Yes, that's why I included the bit after my 'due to' just above.

BUT that minimal page file use only happens in the background
when there is plenty of free resources, so the location of the
page file has no impact on the performance of the system.


If he doesnt say, its reasonable to assume he's talking about Win.


Nope, that is completely silly. If you double the amount
of physical ram, you dont need to double the swapfile.

Its the way the operating system works. Not an option. So whether you
think its silly is not material.

 

[kony]

Don't know. I've been using Linux on and off for a long time, maybe ten
years, and I think its always been that way.

Doesn't windoze default to a max size 2X of memory?

It will create the certain sized pagefile by default, larger
the more memory you have is an inaccurate rough guess that
may or may not apply to all users/uses, but that doesn't
mean it's actually using that much. It will access the
swapfile even with more than enough memory to run
everything, but it will be mostly designating allocations,
not paging out the contents of physical memory (until you
run out of available memory and nothing can be flushed to
use more main memory instead of the pagefile).

 

[kony]

BUT that minimal page file use only happens in the background
when there is plenty of free resources,
False

so the location of the
page file has no impact on the performance of the system.

False again, though of course the less it's used
simultaneous to other I/O, the less it'll matter where it
is.

If he doesnt say, its reasonable to assume he's talking about Win.


Nope, that is completely silly. If you double the amount
of physical ram, you dont need to double the swapfile.

Some would even say the pagefile can then be that much
smaller, it depends a bit on whether the user is just buying
a lot of memory because doing so is in vogue, or buying a
lot of memory to run a lot of memory intensive applications.
Some people with 1GB will use it *all*, and need a lot more
pagefile space than other people with 1GB physical memory
would.

 

[kony]

I run XP Pro.
My mobo does not support SATA.
I have several hard drives. All my HDD's are PATA and 133 MBps

You're about to ask about performance, but didn't tell us
about your particular drives so there is no answer that can
be complete. Obviously all drives don't have the same
performance. This includes different brand's firmware being
better optimized for certain access patterns/uses. It may
not matter much, or it could be an additive difference as
much or more than what channel they're plugged into.

My operating system partition is on the primary master HDD.
I have placed various cache files in a separate partition on a
seperate HDD.

------

QUESTION ONE
For performance, is it better to configure the HDD containing this
Cache Partition on the mobo's *secondary* IDE socket (as either
master or slave). Or could I configure the Cache Partition as
primary slave without loss of performance?

It would be easy to say it's better to put it on a different
PATA channel, but whether it would be a significant enough
different to realize (even in a very isolated generic test
not considering any specifics of your use) is not so
clear-cut.

You might even have other things accessing this 2nd drive
such that the cache files slow down that I/O more than they
would the OS /app drive, particularly considering that once
you have the OS loaded, the app loaded, and of course
sufficient physical memory to hold it, what remains that is
of sinificant I/O are the files that app is working with.
They too should be elsewhere besides on same drive as OS and
the app, but you can only divide up I/O so many different
ways between different drives and channels.

It is far more significant to put the simultaneous I/O on a
different drive than on a different controller channel. If
you are still lacking performance enough that you hope for
more from channel positioning, it's probably time to just
buy faster drives first.

QUESTION TWO
For performance, does it matter if I move a HDD from being master to
being slave on the same IDE cable?
no


For example, is it ok to change
my system HDD from primary master to primary slave?

So long as the system will boot from it (which any system in
the past half-decade or more should be able to do), though
Windows expects it to be on the primary master until you
change the boot.ini file.

 

[Rod Speed]

Rod Speed wrote

Its the way the operating system works.

No it isnt.

Not an option. So whether you think its silly is not material.

Neither is your silly claim that it actually uses twice the size of
the physical ram, regardless of how much physical ram there is.

 

[Rod Speed]

False

Easy to claim. Hell of a lot harder to actually substantiate that claim.

False again,

Easy to claim. Hell of a lot harder to actually substantiate that claim.

though of course the less it's used simultaneous
to other I/O, the less it'll matter where it is.

There is no impact on performance when you have enough physical
ram so that there is no need to swap out physical ram to the swap file.

The only reason Win does that is in case there is a need for more physical
ram than is installed, and that is done with free resources, because its
impossible to predict whether that will ever actually be needed.

Some would even say the pagefile can then be that much smaller,
it depends a bit on whether the user is just buying a lot of memory
because doing so is in vogue, or buying a lot of memory to run a lot
of memory intensive applications. Some people with 1GB will use it
*all*, and need a lot more pagefile space than other people with
1GB physical memory would.

Irrelevant to what the OS can choose to do IN CASE
there is a need for more physical ram than is installed.

 

[Rod Speed]

You're about to ask about performance, but didn't tell us about
your particular drives so there is no answer that can be complete.

Wrong, as always. The answer can obviously
cover all the possibilitys and so be complete.

Obviously all drives don't have the same performance.
This includes different brand's firmware being better
optimized for certain access patterns/uses. It may
not matter much, or it could be an additive difference
as much or more than what channel they're plugged into.

Hardly ever in practice.

It would be easy to say it's better to put it on a different PATA
channel, but whether it would be a significant enough different
to realize (even in a very isolated generic test not considering
any specifics of your use) is not so clear-cut.

You might even have other things accessing this 2nd drive
such that the cache files slow down that I/O more than they
would the OS /app drive, particularly considering that once
you have the OS loaded, the app loaded, and of course
sufficient physical memory to hold it, what remains that is
of sinificant I/O are the files that app is working with.
They too should be elsewhere besides on same drive as OS and
the app, but you can only divide up I/O so many different
ways between different drives and channels.

It is far more significant to put the simultaneous I/O on a
different drive than on a different controller channel. If
you are still lacking performance enough that you hope for
more from channel positioning, it's probably time to just
buy faster drives first.


So long as the system will boot from it (which any system in
the past half-decade or more should be able to do), though
Windows expects it to be on the primary master until you
change the boot.ini file.

Wrong, as always.

 

[Joe S]

My understanding is that unless the pagefile is set to zero,
there's probably going to be some pagefile use even with a large
amount of RAM.

I didn't see any reference to the operating system in use. If its
Linux, IIRC a swapfile is required. I think the recommendation is
about twice the amount of memory. And the Linux system monitor
indicates that it does get used even if there's plenty of real
memory.

I am the OP. Way back in the original post it says I run XP.

 

[Old Guy]

No it isnt.


Neither is your silly claim that it actually uses twice the size of
the physical ram, regardless of how much physical ram there is.

The default swapfile is configured during o/s installation. I didn't
say it was all used, just there. Its not for me to justify or you to
criticize, its just the way it is. Some of the swapfile will get used
even in systems with more real memory than the system could use. Who
cares?

If windoze is installed on a system with 4 gb of memory, why do they
create a default swapfilf of 2 gig? That's silly.

 

[Joe S]

Don't know. I've been using Linux on and off for a long time,
maybe ten years, and I think its always been that way.

Doesn't windoze default to a max size 2X of memory?

See "Virtual Memory in Windows XP" http://aumha.org/win5/a/xpvm.htm
A snippet (see the link for full context) says:

"For any given workload, the total need for virtual addresses will
not depend on the size of RAM alone. It will be met by the sum of RAM
and the page file. Therefore in a machine with small RAM, the extra
amount represented by page file will need to be larger, not smaller,
than that needed in a machine with big RAM." etc etc etc.

 

[Joe S]

Its the way the operating system works. Not an option. So whether
you think its silly is not material.

AFAICT Rod is right.

See "Virtual Memory in Windows XP"
http://aumha.org/win5/a/xpvm.htm

 

[John Weiss]

My understanding is that unless the pagefile is set to zero, there's
probably going to be some pagefile use even with a large amount of RAM.

That is true. As long as there is a pagefile existent, Windoze will make
some use of it. Some apps will do the same.

For example, I have 2 GB total RAM with 1.2 GB available, but there is still
almost 600 MB of the 2 GB pagefile in use.

I reduced the pagefile to 1 GB, but there was no significant change in its
usage.

So, contrary to rodless' implication, pagefile use cannot be eliminated
simply by adding RAM.

I didn't see any reference to the operating system in use.

OP stated WinXP at the beginning.

 

[John Weiss]

My Windows XP defaults to 1536 MB with 1 GB of RAM. I don't know what
it depends on.

Note, however, that the default is NOT a constant-size pagefile. You may
gain a bit in boot time and a bit in performance if you set the min and max
pagefile size to the same value so it is not dynamically resizing. If the
file starts out as a contiguous file, it will also prevent pagefile
fragmentation, which is another minor performance issue.

For minimum RAM configurations, the 150% value is appropriate. However, as
you increase RAM, you do not necessarily have to keep the pagefile in that
proportion. For example, when I increased my laptop RAM from 512 MB to 1.5
GB, I reduced the pagefile from 768 to 512 MB. Total available memory is
still more than original, but much more of it is physical RAM. The
increased "snap" of the system is apparent.

 

[John Weiss]

Easy to claim. Hell of a lot harder to actually substantiate that claim.

You should know, since you're the king of unsubstantiated and
unsubstantiatable claims around here...

 

[John Doe]

Note, however, that the default is NOT a constant-size pagefile.

Mine is.
I thought that odd, but the default is fixed.

 

[Rod Speed]

Rod Speed wrote

The default swapfile is configured during o/s installation.

And that is to let Win manage the page file when the OS is Win.

I didn't say it was all used, just there.

You made that stupid claim about twice the physical ram being 'recommended'

It isnt, particularly when there is enough physical ram so that
the page file isnt used because of a lack of physical ram.

Its not for me to justify or you to criticize, its just the way it is.

Your silly claim about twice the physical ram is nothing like the way it is.

Some of the swapfile will get used even in systems with more real memory than the system could
use. Who cares?

Irrelevant to your silly claim about twice the physical ram.

If windoze is installed on a system with 4 gb of memory, why do they create a default swapfilf of
2 gig?

They dont.

That's silly.

And its clearly not twice the physical ram either.

 

[Rod Speed]

That is true. As long as there is a pagefile existent, Windoze will
make some use of it. Some apps will do the same.

For example, I have 2 GB total RAM with 1.2 GB available, but there
is still almost 600 MB of the 2 GB pagefile in use.

I reduced the pagefile to 1 GB, but there was no significant change
in its usage.

So, contrary to rodless' implication, pagefile use cannot be eliminated simply by adding RAM.

I never ever implied anything of the sort.

 

[Rod Speed]

You should know, since you're the king of unsubstantiated and unsubstantiatable claims around
here...

How odd that we aint seen even a single substantiation from you, ever.

 

[Robert Heiling]

And that is to let Win manage the page file when the OS is Win.


You made that stupid claim about twice the physical ram being 'recommended'

It isnt, particularly when there is enough physical ram so that
the page file isnt used because of a lack of physical ram.

Are you certain that won't be paged, even though a copy remains in ram?

Your silly claim about twice the physical ram is nothing like the way it is.

What puzzles me most about this whole discussion is the lack of mention of the
demand that the running tasks place on memory requirements.

Irrelevant to your silly claim about twice the physical ram.

Yes. The size of physical ram is less important than the total memory required
by the running tasks for program code and data space. That figure plays the most
important role in the size of the pagefile and its role has not even been
mentioned. That is obviously going to vary depending upon what use is made of
the systems and which, and how many, applications are being run concurrently.

Bob