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SSD SLC, for exclusive use by Virtual Memory?

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April 26, 2009 8:18:13 PM

I haven't seen a review where a smallish SLC SSD was used exclusively as a virtual memory device (windows swap file). Would there be a large speed jump configuring this way?

...adding a speedy 4gb ReadyBoost usb drive to a system with 8gb ddr2 ram gave no detectable improvement whatsoever. :( 
April 26, 2009 8:33:05 PM

It would give a nice boost in speed...thats what I do on my SLC 64GB Samsung SSD. Using a USB with ReadyBoost is an interesting idea from Microsoft, but the interface speed is way too slow to notice any gains in performance....regardless of how fast the USB drive is.
April 26, 2009 8:45:52 PM

You got enough ram to not have any virtual memory.

Your better off disableing the page file all together.

I dont run pagefile on and rig of mine over 4g of ram.
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April 26, 2009 9:05:23 PM

pbrigido said:
It would give a nice boost in speed...thats what I do on my SLC 64GB Samsung SSD. Using a USB with ReadyBoost is an interesting idea from Microsoft, but the interface speed is way too slow to notice any gains in performance....regardless of how fast the USB drive is.


Agreed, lol: I initially read some MS balony about ReadyBoost drastically lowering the boot time (I think the article I read said something unbelievable, like from 11seconds to like 1.3seconds). To anyone reading this and thinking about ReadyBoost, you are much better off getting your ram to 4gb instead.

64gb is certainly enough for your OS and swap file, you have both on your SLC SSD? running apps or anything off a normal drive?

I wonder if it'd be advantageous to 1. use a ~$100-120 8gb slc ssd for the swap file/virtual memory, or 2. it it'd be better to get with a single larger (16gb, 32gb, 64gb?) slc ssd for both swap and OS, or 3. RAID0 two slc ssd's for os+swap...
a c 127 G Storage
April 27, 2009 11:15:00 AM

Virtual memory is a technique of advertising more memory than is available in the system. Actually swapping is storing memory on the harddrive because the available RAM is on the low side. This usually only happens when your system is short on memory; so improving the performance of the swap may only be noticeable on systems which are slow and running low on memory. In other words, a fast computer won't swap anyway so why concentrate on that?
April 29, 2009 12:52:47 PM

sub mesa said:
Virtual memory is a technique of advertising more memory than is available in the system. Actually swapping is storing memory on the harddrive because the available RAM is on the low side. This usually only happens when your system is short on memory; so improving the performance of the swap may only be noticeable on systems which are slow and running low on memory. In other words, a fast computer won't swap anyway so why concentrate on that?


I thought windows creates and used a swap file as a matter of course, not a matter of necessity. So I figured if it was going to make a swap file on my hard drive, that it would be using it for some kind of devious and ingenious reasons.
a c 127 G Storage
April 29, 2009 1:23:03 PM

Ingenious? What do you want your OS to do when applications want to use more RAM than is available in a system? Although the pagefile can be disabled, it could introduce problems if you're low on RAM (less than 4GB). It would have no fail-safe option of swapping; if its out of memory it will have to start killing processes, and that can be system processes so your computer gets a blue screen immediately when memory runs out. Pagefiles are there for a reason. But simply creating a 1GB pagefile is not the same as actually using it to "swap"; swapping is actually putting information in the RAM on the harddrive so the RAM gets freed up for other things. That should only happen when your RAM is running low.

So as long as you got enough RAM in your system, your system should not be using the pagefile. Some operating systems are more 'aggressive' with swapping, and so disabling the swap or pagefile would actually be beneficial. But i can't say the same for recent windows versions. Swap is about the least important thing regarding performance on a modern system.
April 30, 2009 6:12:22 AM

hmm... it's clear to me that i need to find a little app that can historically track usage of swap and pagefile -- maybe over several days, so i can see if its being used, and when...
April 30, 2009 8:40:26 AM

Dont waste your time with a single SSD, buy 2 OCZ vertex 32 or 64gb, raid 0, write 450-500mb/sec write 350-400mb/sec numbers speak for themselves....
a c 127 G Storage
April 30, 2009 9:56:05 AM

So? An SSD that always does 40MB/s is going to be faster than 100 of those Vortex disks in RAID0. Sequential performance is not really key to unlocking the storage bottleneck on desktop systems; its non-sequential performance or IOps.

A HDD does 100-200 IOps
a bad SSD does 1000-2000 IOps
a good SSD does 30.000 - 100.000 IOps

That's the only performance numbers you need - MB/s tells you nothing regarding actual performance.
April 30, 2009 12:19:04 PM

sub mesa said:
So? An SSD that always does 40MB/s is going to be faster than 100 of those Vortex disks in RAID0. Sequential performance is not really key to unlocking the storage bottleneck on desktop systems; its non-sequential performance or IOps.

A HDD does 100-200 IOps
a bad SSD does 1000-2000 IOps
a good SSD does 30.000 - 100.000 IOps

That's the only performance numbers you need - MB/s tells you nothing regarding actual performance.

So, what is a 'good SSD' if 100 Vortex in RAID-0 is not good? :) 
a c 127 G Storage
April 30, 2009 5:04:07 PM

Hm, i phrased that poorly actually. What i was meant to say is that, while RAID0 can increase both IOps and throughput, its effects are limited when using software that cannot use the potential of striping RAID, due to it processing only one thing at a time. This is something Windows in particular is susceptible to. In this case, it might be better to have one single SSD which is very fast, because it can speed up the I/O more than multiple disks in RAID0. You also wouldn't need to use RAID-drivers, which are not always doing the work properly (like with JMicron, Promise, Silicon Image, AMD onboard RAID drivers).

100 Vortex in RAID0 will be very fast, for sure. But it's very hard to reach 40MB/s when doing strong random I/O, especially with mixed reads and writes in it. I calculated that 40MB/s Random I/O means in the worst case 81.920 operations, or 82 thousand IOps. No consumer-level SSD can reach this high with this kind of 'worst case' workload, though SSDs are alot faster in this than HDDs are, since they only do 100-300 random IOps, that's it.

I actually searched a bit about the Vertex. It's very different from the OCZ Apex and Core series in that it doesn't use JMicron controller but rather a controller from an Mtron-daughter company, Mtron is already present in the high-performance SSD market and is quite reputable. The benchmarks look alright, but the Vertex is ofcourse a low-cost consumer drive. Its really worth the money i believe. Though regardless of its sequential performance being on par with Intel X25-M, i do believe the latter can produce more IOps than the Vertex is able to, making it faster. It may even beat two vortexes in RAID0. Then again, two Vortexxes will beat the Intel on other areas and will do very well in throughput benchmarks like ATTO, HDTune, HDTach if you care about those (i wouldn't :p ).

It depends on the price i guess. With Intel's recent price cuts the X25-M has become a viable option too for a moderately expensive system. Then again, i certainly don't think two Vertex disks in RAID0 are a bad choice, they have a decent controller it seems and are very different from the Apex and Core series, which use the plagued JMicron controller.
a c 127 G Storage
April 30, 2009 5:08:40 PM



Here's some picture, but i couldn't find real good benchmarks comparing the OCZ Vertex and Intel X25-M. It does show that while their throughput and access times are similar, IOps performance can differ greatly. This is the actual performance that counts when you're using it on your desktop and applications wait for I/O completion and won't respond until the I/O has been done. This is a personal frustration for me since i'm waiting for the computer alot since my head is already 3 steps further. Computers should be ahead of me; they are masters of calculations aren't they? ;-)
May 4, 2009 10:56:54 PM

check OCZ forum, raid 0 vertex, youll see Pwned everything big....ill find link if you really want after, pm if you want it
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