Best use of 3 drives

  • Thread starter Thread starter J A Temple
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J

J A Temple

Hi all, I have a WD 80GB 8MB cache drive but would like to upgrade to 2
Raptors. What would be the best solution for speed? I'm thinking of a
RAID-0 with the old drive as backup (and music files, etc). I seem to
recall that it's best to have the swap file on a separate partition at
least, preferably on a separate drive. However, I would have thought having
it on the dual Raptors would be faster...

What say you, good ppl?

Jat
 
Hi all, I have a WD 80GB 8MB cache drive but would like to upgrade to 2
Raptors. What would be the best solution for speed? I'm thinking of a
RAID-0 with the old drive as backup (and music files, etc). I seem to
recall that it's best to have the swap file on a separate partition at
least, preferably on a separate drive. However, I would have thought having
it on the dual Raptors would be faster...

What say you, good ppl?
Click to expand...

It's really impossible to say what's the best use of 3 disks without
measuring your machine while it's running whatever software you want
to run faster. Money spent on one of those disks may be better spent
on memory, if you're short. perfom.exe is the tool that measures these
things.

raid0 (mirroring) will speed up disk I/O but unless it's your
bottleneck now you won't notice it.

Putting pagefile in a seperate partition is bad. putting it on it's
own disk is good, but again, you won't notice unless sawpping is a
bottleneck, in which case teh money is better spent on memory, unless
you are maxed-out.

I put /tmp and swap and photoshop temp files on a seperate disk, which
is also as a place to put a backup copy of my MP3s and backup images
of a couple systems.
 
J said:
Hi all, I have a WD 80GB 8MB cache drive but would like to upgrade to 2
Raptors. What would be the best solution for speed? I'm thinking of a
RAID-0 with the old drive as backup (and music files, etc). I seem to
recall that it's best to have the swap file on a separate partition at
least, preferably on a separate drive. However, I would have thought having
it on the dual Raptors would be faster...

What say you, good ppl?

Jat
Click to expand...

Good idea using the Raptors in Raid 0, with the WD used as data
storage. Just make sure you backup important stuff to CD or DVD.

Forget about the swapfile; get yourself 1GB of memory and do without the
swapfile. Unless, of course, you are running a program that absolutely
has to have a swapfile (e.g. some versions of Adobe Photoshop.)

If the latter is the case, still get 1GB of memory and a program called
"ramdisk pro." This lets you create a virtual drive using RAM (which
you then use for a swapfile) and is 30 times quicker than your standard
Windows hard-drive-based swapfile. You ***WILL*** notice a huge
difference in performance.


Odie
 
Good idea using the Raptors in Raid 0, with the WD used as data
storage. Just make sure you backup important stuff to CD or DVD.

Forget about the swapfile; get yourself 1GB of memory and do without the
swapfile. Unless, of course, you are running a program that absolutely
has to have a swapfile (e.g. some versions of Adobe Photoshop.)

If the latter is the case, still get 1GB of memory and a program called
"ramdisk pro." This lets you create a virtual drive using RAM (which
you then use for a swapfile) and is 30 times quicker than your standard
Windows hard-drive-based swapfile. You ***WILL*** notice a huge
difference in performance.
Click to expand...

If you don't create a virtual drive, your machine will have more
memory available to use for programs and won't have to swap at all.

In your solution you are forcing windows to swap to a swapfile in
memory, which is slower than windows not having to swap at all.


Al Dykes gave a very good answer. We cannot advice Temple on what to
do unless he has determined IF the harddisk is a bottleneck, and then
for WHICH programs the harddisk is the bottleneck.
If the harddisk is the bottlneck, it is vital to know if that is
because it does lots of random read/writes. (thus needing a good seek
time which a high rpm disk will have) or whether it needs a higher
sequential read/write performance. (In which case a 7200 rpm disk can
be almost as fast as a 10.000 rpm disk and much cheaper)

Marc
 
Marc said:
If you don't create a virtual drive, your machine will have more
memory available to use for programs and won't have to swap at all.

In your solution you are forcing windows to swap to a swapfile in
memory, which is slower than windows not having to swap at all.
Click to expand...

Marc,

You didn't read my post correctly.

No swap file is best, although in my opinion and my researched
experience, a swapfile on a RAM disk is stupendously quicker than your
usual Windows swapfile, and works substantially quicker than is enabled
by Windows' memory management, which I believe is crap.

Odie
 
Marc,

You didn't read my post correctly.

No swap file is best, although in my opinion and my researched
experience, a swapfile on a RAM disk is stupendously quicker than your
usual Windows swapfile, and works substantially quicker than is enabled
by Windows' memory management, which I believe is crap.

Odie
Click to expand...


It should be noted that the suggestions to implement no-pagefile
systems in XP are in the distinct minority, and even if there is some
application for which a ramdisk is apropriate, the statement about
windows memory management in the above paragraph in an utterly
unsupportable paragraph, since the core logic of memory management is
essentially the same for w2k, including very large servers and is
proven quite satisfactory in production service.

It certainly is correct for w/98.
 
Odie said:
No swap file is best, although in my opinion and my researched
experience, a swapfile on a RAM disk is stupendously quicker than your
usual Windows swapfile, and works substantially quicker than is enabled
by Windows' memory management, which I believe is crap.
Click to expand...

Swapfile on a RAM disk?? Is this a joke?
Or is Windows memory management *that* bad?


-WD
 
Marc,

You didn't read my post correctly.
Click to expand...

Aparantly I read it just fine. But it seems that you didn't read MY
post correctly.
No swap file is best, although in my opinion and my researched
experience, a swapfile on a RAM disk is stupendously quicker than your
usual Windows swapfile, and works substantially quicker than is enabled
by Windows' memory management, which I believe is crap.
Click to expand...

Of course a swapfile on a ramdisk is much faster than a swapfile on
harddisk. Just like any file on ramdisk is much faster than a
harddisk.

But that doesn't mean that it is wise to put your swapfile on a
ramdrive.

You have to look at WHY and WHEN a swapfile is used.

You use a swapfile when you don't have enough memory. When you create
a ramdisk you are decreasing the amount of memory available for
applications. This means that windows start swapping much earlier then
woul be the case when you had not created that swapfile.

Look at the following scenarios.
You have machine with 1 GB RAM.
In situation A you create a 500MB ramdrive and put your swapfile on
that. You thus have 500MB available for the OS and applications.
In siutation B you do not create a ramdrive and just have a swapfile
on disk. You have 1000MB available for the OS and applications.

1) Your applications use 250MB ram.
A: The application fits in the 500MB available physical memory and
thus no swapping is needed.
B: The application fits in the 1000MB availabe physical memory and now
swapping is needed.

Result: No performance difference between the configurations

2) You applications use 750MB ram.
A: The system needs to swap 250MB to the swapfile on the RAMdrive.
Even though the ramdrive is very fast, swapping is taking place and
the system is slowed down because of this. The slowdown is not very
big, but it is there.
B: The 750MB fits in the 1000MB, so no swapping is needed.

Result: The configuration with the Ramdrive is marginally slower then
the other configuration.

3) Your applications use 1.5GB ram.
A: The system swaps 500MB to the swapfile on the RAMdrive. And it
swaps 500MB to a swapfile on disk. (or if you don't have a swapfile on
disk your system crashes)
B: The system swaps 500MB to a swapfile on disk.

Result: Both configurations are slowed down considerably due to the
swapping to disk. (the performance loss of the swapping to ramdrive is
neglectable in comparison)

Conclusion: Do not put a swapfile on ramdisk.

Ramdrives are usefull when you have a disk bottleneck on creating temp
files. Lots of applications don't write data to memory but use
tempfiles. (smtp gateways for example) In that situation a ramdrive
can increase performance a lot.

Marc
 
Marc de Vries wrote:

<snip>

Like I said, try it.

If you're short sighted or narrow minded, that's your problem / even
your prerogative.

Odie
 
Odie said:
Marc de Vries wrote:

<snip>

Like I said, try it.

If you're short sighted or narrow minded, that's your problem / even
your prerogative.
Click to expand...

If you've tried it please describe the details of the machine and OS on
which you tried it, the applications which you used to test it, and the
outcome, with some numbers.

Accusing others of being short-sighted or narrow-minded because they don't
immediately accept the brilliance of your notion that flies in the face of
all theory and experience is the tactic of someone who doesn't have any
solid evidence that his belief is correct.
 
Try it yourself before condemning it.


Odie
Click to expand...

Is there anyone here other than Odie that's tried any "ramdisk"
software with w2k/XP and can say what their experiences were and what
applications they use ?

As far as I can tell, Odie is the only advcate.
 
Aparantly I read it just fine. But it seems that you didn't read MY
post correctly.


Of course a swapfile on a ramdisk is much faster than a swapfile on
harddisk. Just like any file on ramdisk is much faster than a
harddisk.

But that doesn't mean that it is wise to put your swapfile on a
ramdrive.

You have to look at WHY and WHEN a swapfile is used.

You use a swapfile when you don't have enough memory. When you create
a ramdisk you are decreasing the amount of memory available for
applications. This means that windows start swapping much earlier then
woul be the case when you had not created that swapfile.

Look at the following scenarios.
You have machine with 1 GB RAM.
In situation A you create a 500MB ramdrive and put your swapfile on
that. You thus have 500MB available for the OS and applications.
In siutation B you do not create a ramdrive and just have a swapfile
on disk. You have 1000MB available for the OS and applications.

1) Your applications use 250MB ram.
A: The application fits in the 500MB available physical memory and
thus no swapping is needed.
B: The application fits in the 1000MB availabe physical memory and now
swapping is needed.

Result: No performance difference between the configurations

2) You applications use 750MB ram.
A: The system needs to swap 250MB to the swapfile on the RAMdrive.
Even though the ramdrive is very fast, swapping is taking place and
the system is slowed down because of this. The slowdown is not very
big, but it is there.
B: The 750MB fits in the 1000MB, so no swapping is needed.

Result: The configuration with the Ramdrive is marginally slower then
the other configuration.

3) Your applications use 1.5GB ram.
A: The system swaps 500MB to the swapfile on the RAMdrive. And it
swaps 500MB to a swapfile on disk. (or if you don't have a swapfile on
disk your system crashes)
B: The system swaps 500MB to a swapfile on disk.

Result: Both configurations are slowed down considerably due to the
swapping to disk. (the performance loss of the swapping to ramdrive is
neglectable in comparison)

Conclusion: Do not put a swapfile on ramdisk.

Ramdrives are usefull when you have a disk bottleneck on creating temp
files. Lots of applications don't write data to memory but use
tempfiles. (smtp gateways for example) In that situation a ramdrive
can increase performance a lot.

Marc
Click to expand...


Well said.

My $0.02;

The size (number of pages) in the pagefile at any given time is not
very relevant from a performance standpoint. What really matters is
the number of page reads/writes per second. The correct description
is; if the total "memory working set" for all the OS and all
applications is less than the physical memory ("page pool") the system
will never need to read or write to the pagefile, for all practical
purposes. On mainframes we used to talk about single-digit pages/sec
to the swap device.

perfmon will tell you your swap I/O rates.

If you use a ramdisk to lock memory pages they are not available in
the page pool, and increase swaping, which, will be faster, granted,
but paging faster than fast paging.

Google "VM working set" for more information.

We frequently found that /tmp was a much better candidate for ram, or
the fastest spindle in the configuration. The problem is that the
size of tmp can swing wildly and it's poor to statically allocate lots
of memory to one function at expense of all other system performance.
 
Yes, I did. I have created ramdisk for Internet temp files. It helped a bit
with browsing speed, but I have found out that removing 50MB (from physical
256MB RAM) caused some performance problems for other applications. So I got
rid of it. Instead I "Empty Temporary Internet Files folder when browser is
closed" and speed improved anyways. With DSL you do not want to cache too
much.
 
Al Dykes said:
Putting pagefile in a seperate partition is bad. putting it on it's
own disk is good, but again, you won't notice unless sawpping is a
bottleneck, in which case teh money is better spent on memory, unless
you are maxed-out.
Click to expand...

I'm not a Linux user, but am pretty sure some distros use separate partition
for swap? Presume Win works differently in that regard; but wouldn't the
swap be faster on a C: if that consisted of 2 Raptors than on D: if that was
my old 7200 WD 8MB 80GB drive?
 
Thank you Odie, Marc, Al + every1 else who replied. You are quite right, I
need to benchmark + verify my needs before asking such a 'loaded', broad
question; but interesting to read your responses nevertheless.

JAT
 
I'm not a Linux user, but am pretty sure some distros use separate partition
for swap?
Click to expand...

Correct. Linux can make special partitions for swapfiles. But there is
very little reason to do so.

I guess that if you want to use a second harddisk for swap, you could
make a small and efficient "filesystem" for that swappartition.
But I doubt whether that makes much difference. Once you are swapping
to disk, your performance plummets so fast, that a small performance
difference in the filesystem of the disk won't matter anymore.
Presume Win works differently in that regard; but wouldn't the
swap be faster on a C: if that consisted of 2 Raptors than on D: if that was
my old 7200 WD 8MB 80GB drive?
Click to expand...

That depends completely on what you are doing on those Raptors. If
they are already very busy with other stuff, (presumable the stuff
that made you buy those Raptors in the first place) then most likely
that old 7200 drive will be faster.

It's not about which disk is faster in theory. It's about which disk
is used a lot and which are idle in your system.

That's why the best rule for placing the swapfile is as follows:
Put it on the least used disk on the most used partition.

Least used disk, because that is the disk that will be fastest in
practice.
Most used partition because switching partitions gives some overhead.
That is also why you shouldn't normally create an extra special
partition for the swapfile on a drive. Only if that partition is the
only partition on the drive would you do that.

But in all cases there is also another rule: when you have to worry
about swapfile performance you need to buy more memory.

Marc
 
Marc de Vries said:
It's not about which disk is faster in theory. It's about which disk
is used a lot and which are idle in your system.

That's why the best rule for placing the swapfile is as follows:
Put it on the least used disk on the most used partition.

Least used disk, because that is the disk that will be fastest in
practice.
Most used partition because switching partitions gives some overhead.
That is also why you shouldn't normally create an extra special
partition for the swapfile on a drive. Only if that partition is the
only partition on the drive would you do that.
Click to expand...


Also if the swapfile were in the most-used partition of
the least-used drive. If a drive were used primarily for
backup, for instance, part of it could be used for a swapfile.

But in all cases there is also another rule:
when you have to worry about swapfile performance
you need to buy more memory.
Click to expand...


Yes, if your motherboard and budget will allow it.
(Mine won't - <sob>).

*TimDaniels*
 
J. Clarke said:
If you've tried it please describe the details of the machine
Click to expand...

AMD XP2600+ CPU
ASUS A7N8X Deluxe board
1GB PC3200 ram (512MB Crucial, 512MB Corsair)

and OS
Click to expand...
Windows 2000 and also Windows XP Pro

which you tried it, the applications which you used to test it,
Click to expand...
Adobe Photoshop 7 (it's all I needed it for)



and the
outcome, with some numbers.
Click to expand...

With numbers? If a person needs numbers then the difference isn't
enough. To me the difference in speed was phenomenal. I didn't need
any benchmark programs for this.

Accusing others of being short-sighted or narrow-minded because they don't
immediately accept the brilliance of your notion that flies in the face of
all theory and experience is the tactic of someone who doesn't have any
solid evidence that his belief is correct.
Click to expand...

I see it differently. Other posters have quoted a number of varying
scenarios using different numbers. See previous posts in this thread.
Those kicking up dust have never tried it and appear to show no notion
of even trying it.
Windows' memory management is crap; trying to draw parallels between
Windows' memory management and placing a swapfile on a ram disk is a
waste of time - chalk and cheese.

You are also sitting in the same camp as those who aren't prepared to
try it. Like I said, stop being so narrow-minded. Applies to you, too.

Try it and then come back with your argument. If you need the software
to try it on, let me know and I'll email it to anyone who wants it.

Until then, I rest my case.


Odie
 
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