US 6,549,977 B1 · Use of deferred write completion interrupts to increase the performance of disk operations

Abstract

A disk array controller reliably improves performance in RAID configurations without the need for a battery backup. Write completion interrupts are queued until a write cache flush has been performed and are then sent to a host system. States of ranges of disk addresses (activity bins) are stored in nonvolatile storage elements associated with the ranges. The states allow rebuild times to be reduced after power failures and drive failures. A range is in a Changing state if at least one of the addresses is the target of a write operation that has been initiated but not completed. The range is in a Stable state if no addresses are the target of an uncompleted write operation. Two additional states are used to identify ranges of disk addresses that have been zeroed or never been written to. The additional states allow substantial reductions in RAID volume creation times.

Claims12

Dependent claims

A method for reliably writing data to a disk drive, the method comprising:

(a) receiving a write command from a host system;
(b) storing, in a cache, write data that is associated with the write command and that is to be written to the disk drive;
(c) storing an identification of the write command;
(d) flushing the cache to force cached write data to be written to disk media;
(e) in response to (d), retrieving the stored identification of the write command;
and
(f) sending a completion interrupt to the host based at least upon the retrieved identification of the write command, whereby the completion interrupt is not sent to the host if a power loss interrupts the completion of the write command after the write data is stored in the cache but before the write data is written to disk media.

4 more elements

Dependencies are inferred from the claim text.

Use of deferred write completion interrupts to increase the performance of disk operations

Life of this patent

Use of deferred write completion interrupts to increase the performance of disk operations

Life of this patent

Abstract

Claims12