m500 now cheap
Micron has given its M500 personal SSD a kick in the pants upwards with its M550 iteration being faster and holding slightly more data courtesy of a Marvel controller. The M500 – review here – stored up to 960GB of data; this M550 moves up to a 1TB maximum capacity. It is made from the same 20nm Micron NAND but replaces the …
newegg.com cheaper (Crucial M500 960GB SATA 2.5" 7mm (with 9.5mm adapter) Internal Solid State Drive CT960M500SSD1 ) 439.99
new definition of "cheap" clearly. Cheaper perhaps
So how then did they add capacity? By reducing the 'reserved' flash normally used to allow the controller to do house keeping, wear leveling and maintain good performance and endurance as the drive fills up.
The increased performance spec is nice but how does the new drive perform when it is > 80% filled?
The problem isn't how full it is. The problem will be if it wears out faster because it has less spare blocks available. It's users with write-mostly usage patterns who'll hit the proble first, if problem there is.
They used 240gb (480, 960) before because the NAND they were using was new and relatively immature, so erred on the side of caution with the parity bits on the NAND, which is what it uses for error correction etc.
They are more comfortable with the stability of the NAND now, so switched to 256gb (512, 1024).
It's the same physical amount of NAND (128gbit dies), just with less parity bits assigned, which means more overall storage capacity available to the user.
Think of it more as the number of hot spares in a disk array - they even call it RAIN; redundant array of independant NAND. If you are comfortable with that the disks you have are reliable, you can assign more of them to the array as capacity, and less of them as hot spares.