A
hybrid disk drive, i.e., a disk drive with two types of permanent storage media (conventional disk media and nonvolatile memory, such as
flash memory), uses its nonvolatile memory in operational
modes other than the power-save or “standby” mode wherein the disks are spun down. In a first additional mode, called a “performance” mode, one or more blocks of write data are destaged from
volatile memory (the disk drive's write cache) and written to the disk and simultaneously one or more data blocks of write data are destaged from the
volatile memory and written to the nonvolatile memory. In a second additional mode, called a “harsh-environment” mode, the disk drive includes one or more environmental sensors, such as temperature and
humidity sensors, and the nonvolatile memory temporarily replaces the disks as the permanent storage media. In a third additional mode, called a “write-inhibit” mode, the disk drive includes one or more write-inhibit detectors, such as a shock sensor for detecting disturbances and vibrations to the disk drive. In write-inhibit mode, if the write-inhibit
signal is on then the write data is written from the
volatile memory to the nonvolatile memory instead of to the disks.