It’s probably worth mentioning quickly how we treat the hiberfile—if you read this and immediately went and did a dir /s /ah hiberfile.sys
you would have found that it’s a pretty big file on disk. The hiberfile is sized by default at 75% of physical RAM. The file is essentially a reservation for hibernation data that will be written out as the system is dropping into hibernation. Typically much less space is actually used, and in the case of our fast startup usage, it’s typically ~10-15% of physical RAM but varies based on drivers, services, and other factors.
The system also treats the hiberfile slightly differently than other files on disk, for example, the Volume Snapshot service ignores it (a small performance benefit.) You can disable hibernation and reclaim this space by running powercfg /hibernate off
from an elevated command prompt. But be aware that if you do this, it will disable hibernation completely, including some nice capabilities like fast startup as well as hybrid sleep, which allows desktop systems to do both a sleep and
hibernate simultaneously so if a power loss occurs you can still resume from the hibernated state. You can also run powercfg /hibernate /size and specify a value between 0 and 100 for the percentage of physical RAM to reserve for the hiberfile – but be careful! Specifying too small a size can cause hibernation to fail.
In general, I recommend leaving it enabled at the default value unless you’re working on a system with extremely limited disk space.
Another important thing to note about Windows 8’s fast startup mode is that, while we don’t do a full “Plug & Play” enumeration of all drivers, we still do initialize drivers in this mode. Those of you who like to cold boot in order to “freshen up” drivers and devices will be glad to know that is still effective in this new mode, even if not an identical process to a cold boot
This new fast startup mode will yield benefits on almost all systems, whether they have a spinning HDD or a solid state drive (SSD), but for newer systems with fast SSDs it is downright amazing. Check out the video below to see for yourself: