Apple's description of the zeroing format method we used fits the description of what we wanted in terms of resetting the SSD to a clean state
Zeroing is not the same operation as TRIM. TRIM marks a block as unused, and if you read it you'll either get random data, or zeros (probably the later). Zeroing marks it as in-use, and if you read it you'll get zeros. The SSD's wear management algorithm will move the latter around as though it were real data, whereas it knows the former is "empty" so it won't bother (so the SSD will be faster). In other words, they don't seem to be using a "clean state" at all, which would explain why there's no difference.
Not only that, but writing to all free space of many SSD's will *drop* their IOPS performance since the drive now has to track *all* sectors in the LBA remap table. This is especially true with Intel drives (even the 2nd gen). Additionally, without TRIM, most drives will then continue to track all LBA's as long as used in that same Mac.
Secondly, the SSD in the Macbook Air really isn't very fast at all
A Macbook Air is just about the worst test of SSD performance, as its SATA and other busswork is run in a much reduced power mode, meaning the bottleneck is not the SSD at all. A worst-case degraded SSD in an Air will still be faster than the other bottleneck in that system.
Allyn Malventano, CTNC, USN
Storage Editor, PC Perspective
