What this does
Disable hibernation or switch to reduced mode to reclaim hiberfil.sys space when you do not use full hibernate.
Windows uses hiberfil.sys for hibernation and some Fast Startup behavior. Reclaiming that space is useful on smaller SSDs.
In plain language, free hibernation file space safely matters because hibernation is enabled and reserved storage is large. People usually start looking this up when Fast Startup created a hibernation file footprint. Windows uses hiberfil.sys for hibernation and some Fast Startup behavior. Reclaiming that space is useful on smaller SSDs.
How and why
In practice, free hibernation file space safely matters because hibernation is enabled and reserved storage is large. Windows uses hiberfil.sys for hibernation and some Fast Startup behavior. Reclaiming that space is useful on smaller SSDs. A good next step is to review leave some free storage on small SSDs. Then decide whether you only needed the explanation or whether you want a practical action page too.
You normally review free hibernation file space safely when you want to understand what Windows is doing, what changes it can influence, and whether it is relevant before you touch settings blindly. Useful things to notice first: leave some free storage on small SSDs; use reduced hibernation mode if you still want Fast Startup; avoid disabling features you rely on without checking the trade-offs; document power-policy changes.
- use reduced mode if you still want Fast Startup
- reboot and recheck disk space
- disable hibernation fully only if you do not need it
- test resume behavior after changing power settings
- disable hibernation only if you do not use it