Intel was rumored to be working on a SandForce based drive for several months now, but even the rumors couldn't encapsulate just how long Intel and SF has worked on this drive. According to Intel, the relationship began 1.5 years ago. Still lacking a 6Gbps controller of their own and wanting to remain competitive with the rest of the market, Intel approached SandForce about building a drive based on the (at the time) unreleased SF-2281 controller. Roughly six months later, initial testing and validation began on the drive. That's right, around the time that OCZ was previewing the first Vertex 3 Pro, Intel was just beginning its extensive validation process.

Codenamed Cherryville, Intel's SSD 520 would go through a full year of validation before Intel would sign off on the drive for release. In fact, it was some unresolved issues that cropped up during Intel's validation that pushed Cherryville back from the late 2011 release to today.

Intel's strenuous validation will eventually make SandForce's drives better for everyone, but for now the Cherryville firmware remains exclusive. Intel wouldn't go on record with details of its arrangement with SandForce, but from what I've managed to piece together the Intel Cherryville firmware is exclusive for a limited period of time. That exclusivity agreement likely expires sometime after the SF-2281 is replaced by a 3rd generation controller. There are some loopholes that allow SandForce to port bug fixes to general partner firmware but the specific terms aren't public information. The important takeaway is anything fixed in Intel's firmware isn't necessarily going to be fixed in other SF-2281 based drives in the near term. This is an important distinction because although Cherryville performs very similarly to other SF-2281 drives, it should be more reliable.

As Intel has been working on this firmware for quite a while, it's likely that the 520 uses an older branch of the SF-2281 firmware that has been updated over the past twelve months.

The BSOD is Back, but Not on Intel

Back in October SandForce announced that it had discovered a firmware issue that resulted in unexpected BSODs on SF-2281 drives on certain platforms. Why it took SandForce several months to discover the bug that its customers had been reporting for a while is a separate issue entirely. SandForce quickly pushed out the firmware to OCZ and other partners. Our own internal testing revealed that the updated firmware seemed to have cured the infamous BSOD.

Just as background, our SSD testing is rarely over once the review goes live. Any drive we recommend gets tossed into a primary use machine somewhere within the company. We keep track of drive behavior, including any bugs or performance issues over time. This long term testing process takes place over months. The results of these long term tests are folded into future reviews and recommendations.

The BSOD is caused by a bug in SandForce's power state logic that ultimately results in the drive disconnecting from the system while it's running. It turns out that Windows isn't a fan of you hot un-plugging the drive it's running on, which results in the BSOD. We had two systems that exhibited the BSOD, both of which were fixed by the update last October.

As luck would have it, our own Brian Klug happened to come across an unexpected crash with his 240GB non-Intel SF-2281 based SSD two weeks ago when he migrated it to another machine. The crash was an F4 BSOD, similar in nature to the infamous BSOD issue from last year. While two of the systems we reproduced the BSOD bug on were cured by last year's firmware update, Brian's system (an X58/Core i7 build) was BSODing regularly playing Battlefield 3. Games end up being a great way to trigger the SF-2281 BSOD issue as they frequently switch between periods of idle and load, which does a good job of stressing the power state logic in SandForce's firmware. I immediately sent Brian an Intel SSD 520 to see if the BSOD remained on Intel's drive. Switching to Cherryville caused Brian's BSODs to go away. Indeed most end user reports of SF-2281 BSODs went away with the fixed firmware, but we've still heard of isolated issues that remain unresolved. Whatever Intel has done with the 520's firmware seems to have fixed problems that still remain in the general SF-2281 firmware.

This is actually a dangerous precedent as it means one of two things. The first possibility is that SandForce has been made aware of flaws in its current firmware and chooses against (or is legally prevented from) disclosing it to its partners. The second possibility, and arguably even worse for SandForce, is that Intel was able to identify and fix a bug in the SF-2281 firmware without SandForce knowing it existed or was addressed. I suspect it's the former but as no one is willing to go on the record about the Intel/SandForce agreement I can't be certain.

Intel did go on record saying that the 520 is expected to have far fewer F4/F7 BSODs than any other SF-2281 drive. I asked Intel if I should read into the phrase "far fewer", but the answer was no - the 520 is expected to have similar reliability to the Intel SSD 510 and 320.

At the end of the day that's what Intel really brings to the table with the 520. As you'll soon see, performance isn't very different compared to other SF-2281 based drives. Intel's biggest advantage comes from the unique firmware that ships with the drive. Intel is also quick to point out that while other SF-2281 manufacturers can purchase the same Intel 25nm MLC NAND used on the 520, only Intel's drives get the absolute highest quality bins and only Intel knows how best to manage/interact with the NAND on a firmware level. While it's nearly impossible to prove most of this, the fact that we're still able to reproduce a BSOD on the latest publicly available SF-2281 firmware but not on the SF-2281 based Intel SSD 520 does say a lot about what you're paying for with this drive.

And you are paying a premium for the 520 compared to other SF-2281 based SSDs on the market today:

Intel SSD 520 Price Comparison
  60GB 120GB 180GB 240GB 480GB
Intel SSD 520 (SF-2281) $149 $229 $369 $509 $999
Kingston HyperX (SF-2281) N/A $205 N/A $420 N/A
OCZ Vertex 3 (SF-2281) $95 $190 $240 $375 $850
Samsung SSD 830 $110 $220 N/A $360 $800

Last year Intel hinted at a move from the consumer market to enterprise server and client markets. The 520's higher price likely won't matter there, but for consumers the higher price is noticeable - particularly with good options from companies like Samsung now available on the market.

The Intel SSD 520
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  • iLLz - Monday, February 06, 2012 - link

    There you go, being all logical and stuff. Reply
  • DanSmith - Tuesday, February 07, 2012 - link

    +1 Reply
  • kyuu - Monday, February 06, 2012 - link

    So, Intel wants people to pay a huge price premium over drives with identical flash and an identical controller? For what? Some validation testing and a custom firmware? Despite the fact that they source their own flash giving them a price advantage over everyone except maybe Samsung? Please.

    Also, the 240GB is *more* than twice as expensive as as the 120GB? Why wouldn't you just buy two 120GB drives then? I doubt the performance difference is even worth noting, and once Intel's own new RST drivers come out that support passing the TRIM command to RAID arrays comes out, you can R0 them and get *better* performance than a single 240GB.
    Reply
  • FunBunny2 - Tuesday, February 07, 2012 - link

    *NOT* identical flash or controller. Anand spent much of the text explaining that. Reply
  • NitroWare - Wednesday, February 08, 2012 - link

    Not sure if the PCB is completely custom or Intel just put their logo on a slightly modified circuit board - and then there is the Bill of Materials for the supporting components.

    Corsair have been claiming publicly they went with a custom PCB for their Force 3 and even put up oscilloscope eye diagrams to 'prove' that their signal integrity as superior to a generic reference PCB
    Reply
  • Coup27 - Monday, February 06, 2012 - link

    Anand, could you please update Bench with the 830 results? They appear to have been forgotten about adding into Bench. Reply
  • Narrlok - Tuesday, February 07, 2012 - link

    I second this request. I was about to post about this as well since I wanted to compare the 830 with this drive. Reply
  • beginner99 - Monday, February 06, 2012 - link

    Well it seems obvious especially also because of the delay that the general advice here is to not touch OCZ and especially Sandforce seems to be more than true. There obviously must be quite a lot of bugs in the sandforce firmware.

    But then the price premium? I don't see it. You can get a crucial m4 that preforms just as good and has a very good track record in terms of reliability. (ignoring this 5000 hr bug...but it doubt even intel would spot that)

    While it is sure a fast and reliable drive, the m4 is too while costing much less. And the Samsung isn't bad either.
    Reply
  • eman17j - Wednesday, February 08, 2012 - link

    they fixed the 5000 hr bug Reply
  • eman17j - Wednesday, February 08, 2012 - link

    Also the newer line ocz came out with uses the Indilix controller Reply

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