How SSDs and new controllers work, new OCZ Vertex 3 Pro review

[Dave76]

There are a lot of details and explanations on SSDs and controllers in this article.
Lots of information, if your interested.
How the controllers work and an explanation on the new 25nm nand limitations.

Of coarse, review of the new Vertex 3 Pro and new SF-2500 controller.

OCZ Vertex 3 Pro Preview: The First SF-2500 SSD

For the past six months I've been working on research and testing for the next major AnandTech SSD article. I figured I had enough time to line up its release with the first samples of the next-generation of high end SSDs. After all, it seems like everyone was taking longer than expected to bring out their next-generation controllers. I should've known better.
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The Architecture
I've covered how NAND Flash works numerous times in the past, but I'll boil it all down to a few essentials.

NAND Flash is non-volatile memory, you can write to it and it'll store a charge even if you remove power from the device. Erase the NAND too many times and it will stop being able to hold a charge. There are two types of NAND that we deal with: single-level cell (SLC) and multi-level cell (MLC). Both are physically the same, you just store more data in the latter which drives costs, performance and reliability down. Two-bit MLC is what's currently used in consumer SSDs, the 3-bit stuff you've seen announced is only suitable for USB sticks, SD cards and other similar media.
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What's New
Everything I've described up to this point applies to both the previous generation (SF-1200/1500) and the new generation (SF-2200/2500) of SandForce controllers. Now let's go over what's new:
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The Unmentionables: NAND Mortality Rate

A 50nm MLC NAND cell can be programmed/erased 10,000 times before it's dead. The reality is good MLC NAND will probably last longer than that, but 10,000 program/erase cycles was the spec. Update: Just to clarify, once you exceed the program/erase cycles you don't lose your data, you just stop being able to write to the NAND. On standard MLC NAND your data should be intact for a full year after you hit the maximum number of p/e cycles.

When we transitioned to 34nm, the NAND makers forgot to mention one key fact. MLC NAND no longer lasts 10,000 cycles at 34nm - the number is now down to 5,000 program/erase cycles. The smaller you make these NAND structures, the harder it is to maintain their integrity over thousands of program/erase cycles. While I haven't seen datasheets for the new 25nm IMFT NAND, I've heard the consumer SSD grade stuff is expected to last somewhere between 3000 - 5000 cycles. This sounds like a very big problem.

Thankfully, it's not.
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With new controllers from SandForce, Intel and Marvell due out this year we're going to see SSD performance go through the roof and SSD prices to continue to fall. We're still a couple months away from knowing exactly what to buy, but if you've been putting off that move to an SSD - 2011 may be the year to finally pull the trigger.

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