SSDs: avoid SandForce controllers

As most people are switching their rotating disk drives to solid state flash drives, I thought I'd write up this note: avoid the SandForce controllers. While they excel in a few tasks, they perform exceptionally poorly in many tasks, like encrypted drives. This is especially a concern for MacBook buyers, where there's a 50% chance you'll get a SandForce controller in your unit.

An SSD is made of two parts, the controller and the flash chips. The flash chips are pretty generic, indeed different units of the same model may have flash chips from different vendors. It's the controller that you want to look at.

One of the most popular controllers is from a company called SandForce. It's popular because they use a unique trick: they compress data on the fly. For compressible data, this leads to the highest read/write speeds of any SSD. Thus, your computer will boot faster using a SandForce controllers, since programs tend to be about 50% compressible.

This compression leads to other desirable features. It reduces the "write amplification" effect of SSDs and increases their "durability". SSDs degrade over time as data is repeatedly modified, and the SandForce compression reduces this effect.

But there is a tradeoff. For incompressible data, the SandForce controllers perform the slowest. Sure, they still perform better than rotating disks, but they have a noticeable performance degradation compared to other SSDs.

An example of incompressible data are things that are already compressed, like ZIP files or movies. But the most important incompressible data are encrypted files, especially full disk encryption.

If you have a notebook computer, you definitely want to enable full disk encryption (like Microsoft BitLocker, or Apple FileVault, or Linux TrueCrypt). That way, if it's stolen or lost, nobody gets your private data, such as those passwords you cache in your browser.

The problem with a SandForce controller is that all its features are lost when using full disk encryption, but all its downsides remain. Thus, if you plan on using an SSD for your notebook computer, you should plan on getting something other than a SandForce controller.

This is a problem for Apple MacBooks. The latest generation of MacBook Retina and MacBook Airs come with either a Samsung SSD using a Samsung controller, or a Toshiba SSD using a SandForce controller. Unfortunately, it's a lottery -- you can't control which SSD you get when buying one. If you get the Samsung controller, it'll work great for FileVault. If you get a Toshiba/SandForce combo, it'll suck for FileVault. To see which one you have, go to AppleMenu -- About This Mac  -- More Info -- System Report -- Serial-ATA and look for something like "Apple SSD SM512E". The "SM" means "Samsung", whereas "TS" means "Toshiba".

Rumor has it that if you don't like what the lottery gave you that you can take it back to the nearest Apple store and exchange it for the one that you want. I haven't tried this out, so I don't know.

Another issue with SandForce controllers is that there has been many buggy firmwares. You can see this with vendors like OCZ that have shipped many firmware updates to fix bugs in their SandForce products. I bought a SandForce based SSD from OCZ that I could never get working, no matter which firmware I used.

These days, Intel SSD and Samsung SSDs have excellent reputations, whereas vendors like OCZ have crap reputation. If I had to buy a new SSD for a desktop or notebook, I'd definitely go with them, even though they are slightly more expensive. But I wouldn't get the Intel 520 SSD because it's SandForce based.

So in summary, while SandForce controllers are probably excellent for certain applications, I recommend avoiding them for generic applications, such as for your notebook.

Update: Rumor is that Toshiba/SandForce drives only go up to 256gigs, so that if you order the 512gig version of the MacBook, you'll get a Samsung drive.