A hard reboot (also known as a cold reboot, cold boot or cold start) is when power to a computer is abruptly turned off, then turned back on. This starts the computer without first performing any shut-down procedure. With many operating systems, especially those using disk caches, after a hard reboot the filesystem may be in an "unclean" state, and an automatic scan of on-disk filesystem structures will be done before normal operation can begin. It may be caused by power failure, be done by accident, or be done deliberately as a last resort to forcibly retrieve the system from instances of a system freeze, critical error or virus-inflicted DoS attack. It can also be used by intruders to access cryptographic keys from RAM, in which case it is called a cold boot attack. The attack relies on the data remanence property of DRAM and SRAM to retrieve memory contents which remain readable in the seconds to minutes after power has been removed.
A soft reboot (also known as a warm reboot) is restarting a computer under software control, without removing power or (directly) triggering a reset line. It usually refers to an orderly shutdown and restarting of the machine.
No comments:
Post a Comment