Gigabyte's i-RAM: Affordable Solid State Storage
by Anand Lal Shimpi on July 25, 2005 3:50 PM EST- Posted in
- Storage
i-RAM as a Paging Drive
One question that we've seen a lot is whether or not the i-RAM can be used to store your pagefile. Since the i-RAM behaves just like a regular hard drive, Windows has no problem using it to store your pagefile, so the "can you" part of that question is easily answered. The real question happens to be, "should you?"We have heard arguments on both sides of the fence; some say that Windows inefficiently handles memory and inevitably pages to disk even when you have memory to spare, while others say that you'd be stupid to put your pagefile on an i-RAM rather than just add more memory to your system. So, which is it?
Unfortunately, this is the type of thing that's difficult to benchmark, but it is the type of thing that's pretty easy to explain if you just sit down and use the product. We set up a machine, very similar to how we would a personal system, but tended to focus on memory hogs - web pages with lots of Flash, Photoshop, etc. Of course, we opened them all up at once, switched between the applications, used them independently, simultaneously, basically whatever we could do to stress the system as it normally would be stressed.
At the same time, we monitored a number of things going on - mainly the size of the pagefile, the amount of system memory used, the frequency of disk accesses, pagefile usage per process... basically everything we could get our hands on through perfmon to give us an idea if Windows was swapping to disk or not.
The end result? There was no real tangible performance difference between putting more memory in the system and using the hard disk for the pagefile or putting less memory in the system and using the i-RAM for the pagefile. Granted, if we had a way of measuring the overall performance, it would have shown that we would be much better off with more memory in the system (it runs faster, and it is accessed much quicker than off the i-RAM).
The only benefit that we found to using the i-RAM to store our pagefile was if you happened to have a couple GBs of older DDR200 memory lying around; that memory would be useless as your main system memory in a modern machine, but it'd make a lot better of a pagefile than a mechanical hard disk.
One more situation we encountered that would benefit from storing your pagefile on the i-RAM was those seemingly random times when Windows swaps to disk for no reason. But for the most part, our system was slower when we had less memory and stored the swapfile in it than when we had more memory and less swap file.
Adobe Photoshop is a slightly different creature as it keeps a scratch disk that is separate from the Windows pagefile. We tested Photoshop and used the i-RAM as our scratch disk, but in all cases it always made more sense to just throw more memory at Photoshop to improve performance where we ran out of memory. If the operations you're performing in Photoshop can fit into system memory, then you'll never touch the scratch disk.
Overall, based on our testing, the i-RAM doesn't make much sense as a paging drive unless you have the spare memory. The problem with "spare" DDR200 memory is that it is most likely in small 64MB, 128MB or maybe 256MB sizes, which doesn't buy you much space on an i-RAM drive. For most people, you're much better off just tossing more memory in your system.
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Hacp - Monday, July 25, 2005 - link
It could be useful for pagefile if you have a couple of old 128-256 DDR 333 or older sticks lying around, especially if your ram slots are filled with 4x 512. This can defenetly improve performance over the hard drive pagefiling, which is horrible. I wish Gigabyte would have done 8 sticks instead of 4. The benefit of 8 sticks is that it will allow users to truley use their old sticks of ram 128,256, etc instead of just 1GB sticks. Right now, the price is too high for the actual I-ram module, and also the price of ddr ram is too much. If Gigabye does this right, they could have a hit, but it does not look like they are moving in the right direction. IMO, 2x or 3x Irams with cheap 512 and 256 sticks of old ram running in a raid onfiguration would be an good solution to the hard drive bottleneck, especially if people these days are willing to pay a premium for the Raptors.Also, nice article Anand!
zhena - Monday, July 25, 2005 - link
mattsaccount you would need 3 cards to run raid 5.Here is one thing that is not mentioned on anandtech in most of the storage reviews, and that is responsiveness (as i like to call it.) Back early in the day when people were starting to use raid 0, most benchmarks showed little improvement in overall system performance, even now the difference between a WD raptor and a 7200rpm drive is little in terms of overall system performance. However most benchmarks don’t reflect how responsive your computer is, it's very hard to put a number on that. When I setup raid 0 back in the day, I noticed a huge improvement while using my computer, but I am sure that the actual boot time didn't increase much. Something with the i-ram card, using it probably feels a lot snappier than using any hard drive, which is very important.
ss284 - Monday, July 25, 2005 - link
Raid 0 has a higher access time than no raid. Unless you were running highly disk intensive applications the snappiness would be attributed to ram, not the harddrive.-Steve
zhena - Monday, July 25, 2005 - link
not at all steve, the access time goes down .5ms at most (don't take my word for it i've tested it with many benchmarks) but raid 0 shines where you need to get small amounts of data fast. if you are looking for a mb of data you get it twice as fast as from a regular harddrive, (assuming around 128k raid blocks). And due to the way regular applications are written and due to locality of reference, thats where responsiveness feel comes from.JarredWalton - Monday, July 25, 2005 - link
RAID 0 would not improve access times. What you generally end up with is two HDDs with the same base access time that now have to both seek to the same area - i.e. you're looking for blocks 15230-15560, which are striped across both drives. Where RAID 0 really offers better performance is when you need access to a large amount of data quickly, i.e. reading a 200MB file from the array. If the array isn't fragmented, then RAID 0 would be nearly twice as fast, since you get both drives putting out their sequential transfer rate.RAID 1 can improve access times in theory (if the controller supports it) because only one of the drives needs to get to the requested data. If the controller has enough knowledge, it can tell the drive with the closer head position to get the data. Unfortunately, that level of knowledge rarely exists. You could then just have both drives try to get each piece of data, and whichever gets it first wins. Then your average rotational latency should be reduced from 1/2 a rotation to 1/4 a rotation (assuming the heads start at the same distance from the desired track). The reality is that RAID really doesn't help much other than for Redundancy and/or heavy server loads with a high-end controller.
Gatak - Monday, July 25, 2005 - link
Um yes. This is what I meant - mirroring (raid1, not raid0) would increase access times as both disks could access different data independently (if the controller was smart). Sorry about the confusion.ss284 - Tuesday, July 26, 2005 - link
I was reffering to raid 0 in my post if you didnt notice. There is no way RAID-0 would lower access times. Its impossible seeing as the data is spanned accross both drives, meaning the seek would be no faster than a single drive, and likely a tiny bit slower because of overhead.Gatak - Monday, July 25, 2005 - link
RAID-0 ought to offer better random read access times as there are two disks that can read independently. Writing would be somewhat slower though as both disks need to be synced.Gatak - Monday, July 25, 2005 - link
I'd like to see some server benchmarks with this. For example:* mail server (especially servers using maildir is generating lots and lots of files)
* web server
* file server
* database server (mysql, for example)
Maybe some other benchmarks :D
mmp121 - Monday, July 25, 2005 - link
He even states that on page 11:
Anand, how about an update with some server / database benchies?
Gigabyte might have something on its hands if it makes the card SATA-II to use the speed of the RAM. 1.6GB/s through a 150MB/s straw is not good. Anyhow, here's looking forward to REV 2.0 of the i-RAM GigaByte!