Before the launch of the Surface Pro, Microsoft copped some significant flack when they announced the amount of free storage space available on the system. As the operating system - in this case a full copy of Windows 8 - takes up a significant amount of space, people felt cheated that they weren't able to have a full 64 or 128 GB for their own data and apps. Many people compared the situation to that of an iPad or even the Surface RT, which give you more of the advertised free space.
Ed Bott of ZDNet feels that a comparison between the Surface Pro and the iPad is unfair, as the former can be used as a full-strength PC complete with traditional desktop Windows applications, while the iPad is more of a consumption device tethered to the App Store. A more appropriate comparison should be made between the Surface Pro and Apple's MacBook Air: both contain ultraportable specs including x86 Intel processors, both have similar amounts of RAM, and both come in 128 GB models.
In a lengthy report, Bott crunched the numbers to discover the Surface Pro and MacBook Air contain very similar amounts of free space after the OS and other partitions are factored in. The MacBook Air in its stock configuration has 92.2 GB of 128 GB available for use (77.3%), while the Surface Pro comes with 89.7 GB free (75.2%). A significant portion of the Surface Pro's storage is taken up by a recovery partition, which if you choose to remove (at no cost to system capabilities) nets you more storage, increasing the amount of free space to 97.5 GB (81.8%).
It's also worth noting that Mac OS X and Windows report storage capacities in different ways. OS X likes to use the decimal (Base 10) system, meaning a drive advertised as 1000 GB will show up as very close to 1000 GB in the OS; Windows, on the other hand, uses the binary (Base 2) system, meaning the same "1000 GB" drive will show up as only 931.5 GB.
Not only that, but the total capacity of the Surface Pro and MacBook Air "128 GB" disks are different. When comparing both in Base 2, the MacBook Air's disk is only 112.2 GB while the Surface Pro's is 119.1 GB - so where did the Air lose 7 GB? As it turns out, the Air's solid state drive contains a hidden EFI and Restore partition amounting to roughly that missing space, which unlike the Surface Pro cannot be re-purposed to add more free space.
Using the Recovery Drive wizard you can transfer the Surface's 7.8 GB recovery partition to a USB flash drive, bumping the total free space on the unit up to 97.5 GB. The MacBook Air's recovery partition cannot be removed, so you're stuck with a maximum of 92.2 GB of free space and less than the Surface Pro after a simple tweak has been applied.
At the end of the day though, both systems have very similar capabilities and very similar free storage space, and the large percentage available on the 128 GB units should be more than enough for day-to-day work.
Source and Images: ZDNet