Maxtor 10K III manual Feature Descriptions

Feature Descriptions

•Advanced Ultra160 SCSI-LVD, Ultra320 SCSI-LVD, Ultra2-LVD, and Ultra-SE with

68-pin wide connector or 80-pin SCA-2 connector

•Superior data integrity:

•352-bit Reed-Solomon quad-burst ECC provides fast on-the-fly correction for small errors and robust software-based correction for larger errors

•EDC internal protection from SCSI bus to media

Many of these features are described in this chapter.

The drive contains a large, segmented buffer in RAM that is used to maximize the throughput for sequential read streams. This cache is organized as a number of separate track line segments. Each track line segment can hold data from one complete track on the media, temporarily assuming the identity of the track for all input/output functions.

The buffer is also used to combine or coalesce I/O data on a track-by-track basis, prior to accessing the disk media. Performance is greatly improved by gathering and combining the data on a track basis rather than on a command basis. With this unique system, multiple commands for a particular track are coalesced in the buffer before accessing the media.

As a result, multiple I/O commands, that address a single track are logically combined to avoid multiple disk accesses on multiple rotations. Since most reads and writes are sequential, this greatly increases throughput for most applications.

￿￿￿24'('6%*The drive supports prefetch. After the controller has copied an entire media track into a cache track line segment, a unique algorithm determines whether:

•The most recently used cache track line (track n) satisfies a read request;

•The cache memory also includes another track line (track n-1) corresponding to the media track preceding the one that was just copied, and;

•There is no other work currently waiting for service by the read/write system.

If all three of these conditions are met, there is a high probability that the host will call for data from the next media track (track n+1). So, the drive controller automatically issues a read for that data and substitutes it for the information in the n-1 track line segment in cache. This process, called prefetch, gives the drive a very high cache hit rate for sequential reads.

6-2 Maxtor Atlas 10K III