我的想法是這樣,60GB的一半跟120GB的一半哪個能有更大的空間讓控制晶片私下使用,60GB連OP1+OP2都一樣小一倍啊

下面這段就講得更清楚了
In theory, read speeds shouldn't be significantly impacted by the drive's free space. But there is a noticeable drop-off on the lower-capacity SF-22xx-based SSDs. Compression is one reason for this. Compressed data has to be decompressed, which requires sufficient free space. SandForce's garbage collection mechanism is a second explanation. Because most of its clean-up happens in the foreground, decompression requires a rotation of scratch space so that the NAND wears out evenly. This is known as wear leveling.


Both factors penalize the 60 GB drives we're rounding up more than the larger models as a result of limited NAND bandwidth, a side-effect of leaning on fewer NAND dies. We're using HD Tune to illustrate.