SMART's new SSD wrings extra juice from MLC flash

Re: "can do 50 full drive writes a day for five years"

There are ways you can minimize flash wear. For example you could first try writing/erasing a block using a tiny current to minimize the wear. Read it and check if the operation stuck. If it hasn't apply a tiny bit more, and check again. This reduces the amount of wear, at the expense of controller complexity.

It is also not clear what degree of overprovisioning this drive applies - it could be that it actually has 2x+ the amount of flash that it exposes to the user. This implicitly both reduces the write amplification (2x over-provisioning means write amplification rate of 1x should be achievable with some clever controller programming) and multiplies the total write endurance on top.

It also doesn't say what the test pattern is. It could be gaining a substantial amount of it's performance through methods such as compression and deduplication being carried out in the disk's formware. Some Sandforce controllers are rumoured to have been doing this for quite a while. The downside of this is that if your data is deduplicated and a block goes bad, you lose all instances of that block. Similarly for compression, losing one block of compressed data actually means losing a greater amount of data. All of this is manageable, but it will negatively affect the expected/rated error rate of the disk.

None of these technologies and approaches are new or revolutionary - it is just an evolution of what we have already had for a long time. But it does buy flash more time until a better, more permanent replacement of the technology is ramped up (e.g. phase change or memristor).

Re: "can do 50 full drive writes a day for five years"

Right. I've dug around their website a bit. Most of the stuff is very light on details, the best I can get is from a whitepaper (http://www.smartstoragesys.com/pdfs/WP003_Guardian_Technology.pdf), which, when you get past all the snazzy graphs going upwards, has a few important things in:

- It includes a "Redundant Array of Memory Elements", so yes, there is a lot of redundancy.

- They "treat each cell individually thereby maximizing the effects of stronger flash elements (i.e. those that exhibit higher performance capability) while minimizing the effects of weaker elements". How they know what is 'strong' and 'weak' though I have no idea.

- A job lot of statistical error correction on reads.

- Lots of cache to reduce writes, with some chunky capacitors for when the power fails.

Most importantly though is that they will (to a certain extent) put their money where their mouth is: they give a 5 year guarantee for up to 25 full drive capacity‐writes/day.

So interesting, but I would like more technical information on how they go about this.

Re: Oh, FFS

SMART generally doesn't sell to consumers; you get pricing by negotiating with an account manager / sales person, so there are no retail resellers, and there's no publicly-available list price.

They do make some pretty slick SSDs though, and, from what I've seen, they follow through on their advertised specifications. Not exactly what you'd call "cheap," but if you've got certain requirements, I can definitely see their kit being the best choice, cost included.