[0x0]

Many filesystems exist that do not run on a "plain" read/write block device, because storage based on flash is more complicated than the old random-sector-access magnetic hard drives. See for example UBIFS and JFFS2 on Linux.

Having full and direct low-level control of on-board SSDs could very well be advantageous for performance and longevity of the flash on modern macbooks. Things like combining TRIM with low-level wear leveling etc.

[zrm]

Taking advantage of the differences between flash and spinning rust only requires that you know which one you're running on.

Moving the wear leveling code into the OS where the filesystem can see it is an interesting idea but why aren't we doing that for all SSDs and operating systems then?

[0x0]

(raw) flash and spinning rust are fundamentally different, because spinning rust drives provide a READ SECTOR and WRITE SECTOR primitive, while raw flash provides READ SECTOR, ERASE (large) BLOCK, WRITE (small) SECTOR primitives. Stuff like UBIFS do try to move the wear leveling code into the OS. But the big players like Windows' NTFS and Mac's HFS were originally designed for the spinning rust primitive, so I guess vendors of flash storage (SSD drives, USB sticks etc) had to deal with providing a translation layer to emulate the spinning rust primitives on top of the nand flash primitives. I'm sure various nand flash vendors have different characteristics / spare blocks / secret sauce / defects that are masked by proprietary firmware, and probably see a significant business advantage on keeping those secret. Even things like building smarts about how a FAT filesystem is likely to have heavy rewrites of the file allocation table compared to file contents, into the firmware for USB sticks where FAT is a likely fs, could prove an advantage. So being a single vendor behind the entire stack from the raw NAND flash memory to the motherboard it's soldered onto to the OS is likely very advantageous.

[zrm]

They have their secret sauce so that legacy software can pretend the SSD is spinning rust. Let them.

Why shouldn't we also demand standard low level primitives so that every OS can do the thing you're describing?

[0x0]

Of course a standard would be nice, but good luck getting everyone to agree on one before the end of the century :)

[throwwit]

Already implemented in faster DSP from what I gather... http://arstechnica.com/apple/2011/12/apple-lays-down-half-a-...