Emc Corporation

Jeffrey M Lasker

James M McGillis

A disk storage subsystem includes both volatile and non-volatile portions of memory. In response to a write command from a host computer, the controller allocates a predetermined number of memory blocks in the non-volatile cache memory and allocates a corresponding number of blocks in the volatile memory. Host supplied write data is then stored in the allocated non-volatile memory blocks. The data may also be mirrored in additional non-volatile memory. Immediately thereafter the subsystem sends an acknowledge signal to the host. The subsystem then performs a DMA operation to copy the write-data from the non-volatile memory blocks to the volatile memory blocks. The write-data is then stored on a disk drive at which point the non-volatile memory may be de-allocated. Subsequent reads of the given data may be read from the volatile memory, reducing disk access time. In the event of a power failure, data stored in the non-volatile memory but not yet written to disk is preserved. In the event of a disk controller failure, the non-volatile memory modules may be transferred to a functioning disk controller for recovery.

Disk controller with volatile and non-volatile cache memories

A disk controller and method for transferring data from a host computer to a cache memory of the disk controller and transferring data from the cache memory to disk drives coupled to the disk controller. Received data to be written to disk by the disk controller is stored in a memory within the disk controller. A host I/O processor modifies certain locations within the memory to indicate to a disk I/O processor that the data is in memory and can be written to disk by the disk I/O processor. In this manner intervention of a controller microprocessor is minimized and disk controller performance is improved.

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Marlboro, MA, United States of America

Jeffrey M Lasker