The SSD Relapse: Understanding and Choosing the Best SSD
by Anand Lal Shimpi on August 30, 2009 12:00 AM EST- Posted in
- Storage
Intel's X25-M 34nm vs 50nm: Not as Straight Forward As You'd Think
It took me a while to understand exactly what Intel did with its latest drive, mostly because there are no docs publicly available on either the flash used in the drives or on the controller itself. Intel is always purposefully vague about important details, leaving everything up to clever phrasing of questions and guesswork with tests and numbers before you truly uncover what's going on. But after weeks with the drive, I think I've got it.
| X25-M Gen 1 | X25-M Gen 2 | |
| Flash Manufacturing Process | 50nm | 34nm |
| Flash Read Latency | 85 µs | 65 µs |
| Flash Write Latency | 115 µs | 85 µs |
| Random 4KB Reads | Up to 35K IOPS | Up to 35K IOPS |
| Random 4KB Writes | Up to 3.3K IOPS | Up to 6.6K IOPS (80GB) Up to 8.6K IOPS (160GB) |
| Sequential Read | Up to 250MB/s | Up to 250MB/s |
| Sequential Write | Up to 70MB/s | Up to 70MB/s |
| Halogen-free | No | Yes |
| Introductory Price | $345 (80GB) $600 - $700 (160GB) | $225 (80GB) $440 (160GB) |
The old X25-M G1
The new X25-M G2
Moving to 34nm flash let Intel drive the price of the X25-M to ultra competitive levels. It also gave Intel the opportunity to tune controller performance a bit. The architecture of the controller hasn't changed, but it is technically a different piece of silicon (that happens to be Halogen-free). What has changed is the firmware itself.
The old controller
The new controller
The new X25-M G2 has twice as much DRAM on-board as the previous drive. The old 160GB drive used a 16MB Samsung 166MHz SDRAM (CAS3):
Goodbye Samsung
The new 160GB G2 drive uses a 32MB Micron 133MHz SDRAM (CAS3):
Hello Micron
More memory means that the drive can track more data and do a better job of keeping itself defragmented and well organized. We see this reflected in the "used" 4KB random write performance, which is around 50% higher than the previous drive.
Intel is now using 16GB flash packages instead of 8GB packages from the original drive. Once 34nm production really ramps up, Intel could outfit the back of the PCB with 10 more chips and deliver a 320GB drive. I wouldn't expect that anytime soon though.
The old X25-M G1
The new X25-M G2
Low level performance of the new drive ranges from no improvement to significant depending on the test:
Note that these results are a bit different than my initial preview. I'm using the latest build of Iometer this time around, instead of the latest version from iometer.org. It does a better job filling the drives and produces more reliable test data in general.
The trend however is clear: the new G2 drive isn't that much faster. In fact, the G2 is slower than the G1 in my 4KB random write test when the drive is brand new. The benefit however is that the G2 doesn't drop in performance when used...at all. Yep, you read that right. In the most strenuous case for any SSD, the new G2 doesn't even break a sweat. That's...just...awesome.
The rest of the numbers are pretty much even, with the exception of 4KB random reads where the G2 is roughly 11% faster.
I continue to turn to PCMark Vantage as the closest indication to real world performance I can get for these SSDs, and it echoes my earlier sentiments:
When brand new, the G1 and the G2 are very close in performance. There are some tests where the G2 is faster, others where the G1 is faster. The HDD suite shows the true potential of the G2 and even there we're only looking at a 5.6% performance gain.
It's in the used state that we see the G2 pull ahead a bit more, but still not drastic. The advantage in the HDD suite is around 7.5%, but the rest of the tests are very close. Obviously the major draw to the 34nm drives is their price, but that can't be all there is to it...can it?
The new drives come with TRIM support, albeit not out of the box. Sometime in Q4 of this year, Intel will offer a downloadable firmware that enables TRIM on only the 34nm drives. TRIM on these drives will perform much like TRIM does on the OCZ drives using Indilinx' manual TRIM tool - in other words, restoring performance to almost new.
Because it can more or less rely on being able to TRIM invalid data, the G2 firmware is noticeably different from what's used in the G1. In fact, if we slightly modify the way I tested in the Anthology I can actually get the G1 to outperform the G2 even in PCMark Vantage. In the Anthology, to test the used state of a drive I would first fill the drive then restore my test image onto it. The restore process helped to fragment the drive and make sure the spare-area got some use as well. If we take the same approach but instead of imaging the drive we perform a clean Windows install on it, we end up with a much more fragmented state; it's not a situation you should ever encounter since a fresh install of Windows should be performed on a clean, secure erased drive, but it does give me an excellent way to show exactly what I'm talking about with the G2:
| PCMark Vantage (New) | PCMark Vantage HDD (New) | PCMark Vantage (Fragmented + Used) | PCMark Vantage HDD (Fragmented + Used) | |
| Intel X25-M G1 | 15496 | 32365 | 14921 | 26271 |
| Intel X25-M G2 | 15925 | 33166 | 14622 | 24567 |
| G2 Advantage | 2.8% | 2.5% | -2.0% | -6.5% |
Something definitely changed with the way the G2 handles fragmentation, it doesn't deal with it as elegantly as the G1 did. I don't believe this is a step backwards though, Intel is clearly counting on TRIM to keep the drive from ever getting to the point that the G1 could get to. The tradeoff is most definitely performance and probably responsible for the G2's ability to maintain very high random write speeds even while used. I should mention that even without TRIM it's unlikely that the G2 will get to this performance state where it's actually slower than the G1; the test just helps to highlight that there are significant differences between the drives.
Overall the G2 is the better drive but it's support for TRIM that will ultimately ensure that. The G1 will degrade in performance over time, the G2 will only lose performance as you fill it with real data. I wonder what else Intel has decided to add to the new firmware...
I hate to say it but this is another example of Intel only delivering what it needs to in order to succeed. There's nothing that keeps the G1 from also having TRIM other than Intel being unwilling to invest the development time to make it happen. I'd be willing to assume that Intel already has TRIM working on the G1 internally and it simply chose not to validate the firmware for public release (an admittedly long process). But from Intel's perspective, why bother?
Even the G1, in its used state, is faster than the fastest Indilinx drive. In 4KB random writes the G1 is even faster than an SLC Indilinx drive. Intel doesn't need to touch the G1, the only thing faster than it is the G2. Still, I do wish that Intel would be generous to its loyal customers that shelled out $600 for the first X25-M. It just seems like the right thing to do. Sigh.
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Mr Perfect - Tuesday, September 1, 2009 - link
Probably demand. When I saw that price, I shopped around to see what was going on. Answer? Everyone else seems to be out of stock.Naccah - Tuesday, September 1, 2009 - link
I've been waiting to get an SSD till Win 7 released hoping that the prices would have stabilized somewhat by that time. The recent price fluctuation is disturbing as well as the availability of the X25 G2. When the G2 first hit Newegg I was surfing the site and could have grabbed one for $230, but like I said I was content to wait. Now I'm having second thoughts! and wondering if I should grab one if the price goes down again.gfody - Tuesday, September 1, 2009 - link
That doesn't explain the 160gb - it's not even in stock yet. I have been waiting a month for this drive to be in stock and here they more than double the price one day before the ETA date! It's an outrage.. if I'd known the drive was $1000 I would have bought something else.Way to screw your customers Newegg
araczynski - Tuesday, September 1, 2009 - link
A) your intro has the familiar smell of tomshardware, you'd do to be without that, its unbecoming.B) your final words smell of the typical big corp establishment mentality; bigger, faster, more expensive, consumers want! while if the market is any indication, is completely the opposite of the truth. people want 'good enough' for cheap, as the recent Wired magazine article more or less said. granted, Wired isn't the source for indepth technical reading, but it is a good source sometimes of getting the pulse of things...sometimes, still, more often than anything coming out of the mouths of the big corps.
C) everything in between A and B is great though :) Please leave the opinions/spins to the PR machines.
Personally, the cost of these things is still more than i'm willing to pay for, for any speed increase. the idiotic shenanigans of firmwares and features only present after special downloads/phases of the moon make me just blow off the whole technology for a few more years. I'll revisit this in say 2 or 3 years, perhaps the MLC's will finally die off and the SLC's (unless i have the 2 backwards) or something better rolls out with a longer lifespan.
Anand Lal Shimpi - Tuesday, September 1, 2009 - link
A) My intention with the intro was to convey how difficult it was for me to even get to the point where I felt remotely comfortable publishing this article. I don't like posting something that I don't feel is worthy of the readership's reception. My sincere apologies if it came off as arrogant or anything other than an honest expression of how difficult it was to complete. I was simply trying to bring you all behind the scenes and take you into the crazy place that's my mind for a bit :)B) I agree that good enough for cheap is important, hence my Indilinx recommendation at the end. But we can't stifle innovation. We need bigger, better, faster (but not necessarily more expensive, thank you Moore's Law) to keep improving. I remember when the P3 hit 1GHz and everyone said we don't need faster CPUs. If we stopped back then we wouldn't have the apps/web we have today since developers can count on a large install base of very fast processors.
Imagine what happens in another decade when everyone has many-core CPUs in their notebooks...
Take care,
Anand
DynacomDave - Tuesday, September 29, 2009 - link
First - Anand thanks for the good work and the great article.I too have an older laptop that has a PATA interface that I'd like to upgrade with an SSD. I contacted Super Talent about their MasterDrive EX2 - IDE/PATA. Their response was; We only use Indilinx controller for SATA drives, like UltraDrive series. We use Phison controller for EX2/IDE drives.
I want to improve performance not degrade it. I don't know if this will perform like the Indilinx or like the old SSDs. Can anyone help me with this?
bji - Tuesday, September 1, 2009 - link
There are a few more smaller players in the SSD controller game that don't ever show up in these reviews. They are Silicon Motion and Mtron. The reason I am interested in them is because I have a laptop that is PATA only (it's old I know but I love it and I want to extend its life with an SSD), and I am trying to get an SSD that works in it.Turns out the Mtron MOBI SSDs are not compatible with this laptop. I have no idea why. So I have put an order into eBay for an SSDFactory SSD and am crossing my fingers that it will work.
Mtron makes SATA SSD drives so they could be included in these reviews, and I don't know why they are excluded. It would be interesting to see how their controllers stack up. I personally own two Mtron SSD drives (both 32 GB SLC drives) that I tried to get to work in my laptop and failed to - so one is now the system disk in my desktop and it is very fast (at least compared to platter drives, maybe not compared to newer SSDs). The other one I am still trying to find a use for.
The only Silicon Motion controller drives I have seen are PATA drives so they clearly are a different beast than the SATA drives typically reviewed in these articles. But I would still be interested in seeing the numbers for the Silicon Motion controller just to get an idea of how well they stack up against the other controllers, especially for the 4K random writes tests. The PATA interface ought not to be the limiting factor for that test at least.
paesan - Tuesday, September 1, 2009 - link
I see NewEgg has a Patriot Troqx and a Patriot Torqx M28. What is the difference in the 2 drives.paesan - Tuesday, September 1, 2009 - link
After reading thru the Patriot forum I found the differences. The M28 has 128MB cache compared to 64MB cache on the non M28. The biggest difference is the M28 uses a Samsung controller instead of the Indilinx controller on the non M28. I wonder why they switched controllers.valnar - Tuesday, September 1, 2009 - link
It seems to be that using trim would make a "used" SSD faster, no doubt, but is it required? Would it be okay to buy an SSD for a Windows XP box and just set and forget it? Even used and fragmented, it appears to be faster than any hard drive. My second question is longevity. How long would one last compared to a hard drive?