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.

Used vs. New Performance: Revisited All Indilinx Drives Are Built Alike
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  • sotoa - Friday, September 04, 2009 - link

    Another great article. You making me drool over these SSD's!
    I can't wait till Win7 comes to my door so I can finally get an SSD for my laptop.
    Hopefully prices will drop some more by then and Trim firmware will be available.
    Reply
  • lordmetroid - Thursday, September 03, 2009 - link

    I use them both because they are damn good and explanatory suffixes. It is 2009, soon 2010 I think we can at least get the suffixes correct, if someone doesn't know what they mean, wikipedia has answers. Reply
  • AnnonymousCoward - Saturday, September 05, 2009 - link

    As someone who's particular about using SI and being correct, I think it's better to stick to GB for the sake of simplicity and consistency. The tiny inaccuracy is almost always irrelevant, and as long as all storage products advertise in GB, it wouldn't make sense to speak in terms of GiB. Reply
  • Touche - Thursday, September 03, 2009 - link

    Both articles emphasize Intel's performance lead, but, looking at real world tests, the difference between it and Vertex is really small. Not hardly enough to justify the price difference. I feel like the articles are giving an impression that Intel is in a league of its own when in fact it's only marginally faster. Reply
  • smjohns - Tuesday, September 08, 2009 - link

    This is where I struggle. It is all very well quoting lots of stats about all these drives but what I really want to know is if I went for Intel over the OCZ Vertex (non-turbo) where would I really notice the difference in performance on a laptop?

    Would it be slower start up / shut down?
    Slower application response times?
    Speed at opening large zipped files?
    Copying / processing large video files?

    If the difference is that slim then I guess it is down to just a personal preference....
    Reply
  • morrie - Thursday, September 03, 2009 - link

    I've made it a habit of securely deleting files by using "shred" like this: shred -fuvz, and accepting the default number of passes, 25. Looks like this security practice is now out, as the "wear" on the drive would be at least 25x faster, bringing the stated life cycles closer to having an impact on drive longevity. So what's the alternative solution for securely deleting a file? Got to "delete" and forget about security? Or "shred" with a lower number of passes, say 7 or 10, and be sure to purchase a non-Intel drive with the ten year warranty and hope that the company is still in business, and in the hard drive business, should you need warranty service in the outer years... Reply
  • Rasterman - Wednesday, September 16, 2009 - link

    watching too much CSI, there is an article somewhere i read by a data repair tech who works in one of the multi-million dollar data recovery labs, basically he said writing over it once is all you should do and even that is overkill 99% of the time. theoretically it is possible to even recover that _sometimes_, but the expense required is so high that unless you are committing a billion dollar fraud or are the secretary to osama bin laden no one will ever try to recover such data. chances are if you are in such circles you can afford a new drive 25x more often. and if you have such information or knowledge wouldn't be far easier and cheaper to simply beat it out of you than trying to recover a deleted drive? Reply
  • iamezza - Friday, September 04, 2009 - link

    1 pass should be sufficient for most purposes. Unless you happen to be working on some _extremely_ sensitive/important data. Reply
  • derkurt - Thursday, September 03, 2009 - link

    quote:

    So what's the alternative solution for securely deleting a file?


    I may be wrong on this, but I'd assume that once TRIM is enabled, a file is securely deleted if it has been deleted on the filesystem level. However, it might depend on the firmware when exactly the drive is going to actually delete the flash blocks which are marked as deletable by TRIM. For performance reasons the drive should do that as soon as possible after a TRIM command, but also preferably at a time when there is not much "action" going on - after all, the whole point of TRIM is to change the time of block erasing flash cells to a point where the drive is idle.
    Reply
  • morrie - Thursday, September 03, 2009 - link

    That's on a Linux system btw

    As to aligning drives...how about an update to the article on what needs to be done/ensured, if anything, for using the drives with a Linux OS?
    Reply

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