Among the many improvements expected in Windows 10, we now have another to add to the list. In a new post on its Blogging Windows blog, Microsoft says Windows 10 will take up less space on disk by compressing system files when possible and doing away with on-disk recovery images.
Microsoft describes the new space-saving measures built into Windows 10 as follows:
With current builds, Windows can efficiently compress system files. That gives back approximately 1.5GB of storage for 32-bit and 2.6GB of storage for 64-bit Windows. Phones will also be able to use this same efficient compression algorithm and likewise have capacity savings with Windows 10.
We are also redesigning Windows’ Refresh and Reset functionalities to no longer use a separate recovery image (often preinstalled by manufacturers today) in order to bring Windows devices back to a pristine state. This reduces Windows’ storage footprint further as the recovery image on typical devices can range in size from 4GB to 12GB, depending on the make and model. Phones already have a storage-optimized recovery solution, so, unlike compression, this enhancement is only for tablets, laptops, and desktops.
With 64-bit Windows and the most conservative recovery image size that Microsoft cited, Windows 10 could reduce its footprint as much as 6.6GB with these new methods. That may not sound like much, but owners of smaller SSDs and mobile devices running Windows will probably be happy for every spare byte of free space.
System file compression can incur a performance hit, so the Windows 10 installer will also evaluate each system to determine whether these space-saving measures will negatively impact performance before compressing system files during installation. The two most important factors that the installer will consider are the amount of RAM in a system and the performance of the CPU at hand.
It's less clear how system recovery will work without a separate recovery image. Microsoft says "the Refresh and Reset functionalities will instead rebuild the operating system in place using runtime system files," but doesn't elaborate further. It's probably a safe bet that we'll learn more as Windows 10 nears release.