Writing to storage disks using a differently sized sector format than that of the storage disk require sector edges to be read from sectors of the disks before awrite operation can occur. Write operations consequently incur a penalty by having to pre-read sector edges. A sector-edge cache avoids the performance penalty by storing sector edges obtained from the sectors during previously executed read and write operations. Rather than pre-reading 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.
