Sandforce SSD Firmware Version Confusion

[Apoptosis]

Sandforce SSD Firmware Version Confusion

What SF-1200 based SSD should I buy? I have been asked that question numerous times in recent weeks and to be honest it's a great question. Rumors are going around that OCZ Technologies has a special firmware revision that uncaps random 4K write performance. Other companies offer Sandforce SF-1200 series controllers in their Force series and don't have the performance cap. To be honest the firmware situation with Sandforce drives is confusing so we went straight to Sandforce to try to get some answers.

This chart is shows that internally that Sandforce has three firmware types, but it doesn't help explain what the firmware is on the drives that review sites are reviewing or the drives that you are buying this very second. It also appears that they are leaving it up to their customers to pick and choose what firmware versions they want to release and that RC firmware packages have been released to the channel even though their classification doesn't list those firmware versions as being channel ready. Still digging for the truth from Sandforce I asked what is the MP firmware revision for the Sandforce SF-1222 controller and was told something mildly shocking.

Article Title: Sandforce SSD Firmware Version Confusion
Article URL: http://www.legitreviews.com/article/1312/1/

[rob482]

If you take a Mushkin Callisto 60GB SSD you'll find that it has 55.8GB of free space. The drive has 64GB of MLC NAND on it, so that means 8.2GB or 13% is being reserved for OP.

60GB ~ 55.8GiB

A HD labeled as 60GB means actually 60 billion bytes (GB used as SI unit). Windows displays 55.8GB but actually means 55.8 GiB. This nothing new.

This mistake is quite embarrassing...

http://en.wikipedia.org/wiki/Gibibyte

[Apoptosis]

Embarrassing?

The drive has 64GB of space and a portion of it has been reserved for wear leveling. We aren't talking about bytes and conversions of bytes to GB here. The whole article was about firmware updates and how much space they are reserving on the drives. I think you missed the point of the entire article.

Might want to look at this - http://forums.legitreviews.com/about28296.html

The provisioning of a Sandforce drive (taking out FW, bad blocks, and erase pool) is the baseline 0%. So it is 128,000,000,000 bytes as the baseline for a 128GB drive (same capacity as the popular 128GB indilinx 'barefoot' drives). The overprovisioning is then a simple calculation (all in the decimal number system):

OP% = (128-100)/100 = 28%
OP% = (128-120)/120 = 6.67% round up to 7%

It is not based upon the raw memory capacity which would give different numbers for both 28% and 7%, namely 37% and 14.5%, respectively.

This is how Sandforce is coming up with 100GB and 120GB drives... It's the same physical hardware with the differences being done in the provisioning that is set in the firmware version that is installed on the drives.

100GB drives have 28% over-provisioning
120GB drives have 7% over-provisioning.

Those equations were given to my by SandForce

[rob482]

nevertheless, the sencence I quoted is simply wrong.

[JamieKitson]

rob482 is right, the 13% figure is wrong, the 55.8GiB figure is not due to the over provisioning, see also this:

Although most manufacturers of hard disk drives and flash-memory disk devices define 1 gigabyte as 1000000000bytes, software like Microsoft Windows reports size in gigabytes by dividing the total capacity in bytes by 1073741824, while still reporting the result with the symbol "GB". This practice is a cause of confusion, as a hard disk with a manufacturer-rated capacity of 400 gigabytes might be reported by the operating system as only "372 GB", for instance.

http://en.wikipedia.org/wiki/Gigabyte#C ... _confusion

[JamieKitson]

Also you don't follow your own reasoning, if the 7% figure is actually 13% then the 28% figure would actually be closer to 35% if you had a drive to measure. 100GB ~ 93 GiB, (128 - 93) / 100 = 35.