Total capacity requirement for Lenovo ExpressCache is around 142 M.
The Lenovo ExpressCache software provided is designed only for the ThinkPad 16GB mSATA Solid State Cache Drive (product part number: 0B47309). For the mSATA solid-state drives that come with your computer, use the Lenovo ExpressCache software preinstalled on your computer.
If your system was built with the 16GB mSATA drive , but the ExpressCache software was not installed, please refer to the following document
Lenovo Support: Hard Drives: Reference Guide - A list of other internal and external notebook hard drives. Also has additional information which includes: User Handling Tips for Hard Drives, Lenovo Hard Drive Quick Test, Avoiding Hard Drive Damage, and Lenovo Hard Disk Drive Retention program information.