A system and method for fast ("warm") reboot of a file server is provided, which skips certain conventional boot processes when circumstances warrant, in order to reduce server downtime. In particular, time is saved by avoiding a full shutdown of the processor and memory, and by causing the firmware to refrain from a full clearance of the file server memory. Instead, the firmware accesses a retained copy of the storage operating system kernel from a reserved location in the file server memory so that an operative version of the kernel is reestablished at the appropriate address space in memory without requiring a time-consuming read of the kernel image from disk. In addition, other "normal" (cold) reboot operations such as full memory tests, hardware checks and memory zeroing are avoided as appropriate—saving further time in the overall reboot process, while still attaining the desired reinitialization of key applications and functions.