US 7,277,986 B2 · Sector-edge cache

Abstract

Software that writes to storage disks using a differently sized sector format than that of the storage disks can require sector edges to be read from sectors of the disks before the write operation can occur. Write operations can consequently incur a performance penalty by having to pre-read sector edges. A sector-edge cache avoids this performance penalty by storing sector edges obtained from the sectors during previously executed read and write operations. Instead of having to pre-read a sector edge from disk during a write operation, an input/output controller can examine the sector-edge cache to determine if each appropriate sector edge is already present and then combine new data with that cached sector edge. RAID-5 implementations, which use a read-modify-write process to perform write operations, benefit from sector caches by reading and caching sector edges during the read phase so that no additional pre-reads are needed during the write phase.

Claims20

Dependent claims

A method of handling input/output (I/O) requests to a storage disk, wherein the I/O requests use a different sector size format than that of the storage disk, the method comprising:

receiving an I/O request for a read operation at a logical address of a virtual disk;
determining a logical sector associated with the logical address;
mapping the logical sector to a portion of a physical sector of the storage disk;
determining a sector edge of the physical sector;
and
storing the sector edge in a cache memory.

3 more elements

Dependencies are inferred from the claim text.

Sector-edge cache

Life of this patent

Sector-edge cache

Life of this patent

Abstract

Claims20