Hibernation (computing)

When hibernation begins, the computer saves the contents of its random access memory (RAM) to a hard disk or other non-volatile storage.

[4] The system can have a total loss of power for an indefinite length of time and then resume to the original state.

Most desktops also support hibernation, mainly as a general energy saving measure and allows for replacement of a removable battery quickly.

A system in sleep mode only needs to power up the CPU and display, which is almost instantaneous.

On the other hand, a system in sleep mode still consumes power to keep the data in the RAM, and thus cannot last indefinitely, as hibernation can.

[6] Hibernation is a means of avoiding the burden of saving unsaved data before shutting down and restoring all running programs and re-opening documents and browser tabs.

Both hibernation and sleep preserve memory fragmentation and atrophy that lead to mobile devices working poorer the longer they run without a full reboot.

[7] It is made possible in part due to the sleep and protected mode opcodes in the Intel 386 CPU.

The LTE would sense low battery and prevented data loss by making use of a hidden partition.

A hidden system file named "hiberfil.sys" in the root of the boot partition is used to store the contents of RAM when the computer hibernates.

Windows 7 introduced compression to the hibernation file and set the default size to 75% of the total physical memory.

[18] Microsoft also recommends that the size be increased using the powercfg.exe tool in some rare workloads where the memory footprint exceeds that amount.

[20] According to Microsoft, a regular hibernation includes more data in memory pages which takes longer to be written to disk.

In comparison, when the user session is closed, the hibernation data is much smaller and therefore takes less time to write to disk and resume.

Hibernation is often underused in business environments as it is difficult to enable it on a large network of computers without resorting to third-party PC power management software.

Safe Sleep capability was added in Mac models starting with the October 2005 PowerBook G4 (Double-Layer SD).

This approach combines the benefits of sleep mode and hibernation: The machine can resume instantaneously, and its state, including open and unsaved files, survives a power outage.