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Disk Drive and Integrated Circuit Nonvolatile Memory Combined for Increased Performance, Lower Power

IP.com Disclosure Number: IPCOM000015686D
Original Publication Date: 2002-Jun-24
Included in the Prior Art Database: 2003-Jun-20
Document File: 1 page(s) / 43K

Publishing Venue

IBM

Abstract

Disclosed is a method of improving the performance and lowering the power requirements of a disk drive by adding nonvolatile memory elements, such as FeRAM, to the magnetic head and media storage elements.

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  Disk Drive and Integrated Circuit Nonvolatile Memory Combined for Increased Performance, Lower Power

Disclosed is a method of improving the performance and lowering the power requirements of a disk drive by adding nonvolatile memory elements, such as FeRAM, to the magnetic head and media storage elements.

Toshiba has announced that they will have 32 Mbit FeRAM sample chips by the end of 2001. The stated write access time is 35-50 nS. (EE Times, June 4, 2001 page 34). If the chips can process data that is 32 bits wide, then they can write a sector of data (512 Bytes) in 4.5-6.4 uS. Even the top-of-the-line 15K RPM SCSI hard disk drives take from
8.6 to 12.4 uS to write a sector and this does not count the average latency of 2000 uS! The 32 Mbit chip could contain 8192 512-Byte sectors. The access time of these parts is significantly improved over current (EEROM) nonvolatile electronic memory. Current nonvolatile memory, such as EEROMs, is significantly slower than accessing the rotating magnetic media, so EEROMs would not allow performance advantages over current disk drive technology.

The cost per megabyte of the nonvolatile memory IC's is substantially greater than the cost per megabyte of the disk drive's current magnetic head/media storage. This higher cost is why the disk drive's magnetic head/media storage will not be replaced by memory IC's in the foreseeable future. But there are some significant advantages of these nonvolatile memory IC's and if they were to be combined with the drives' native storage, an improved disk drive could emerge.

Disk drive performance improvements by adding fast electronic nonvolatile memory in disk drives:

Use the FeRAM for spare sectors. Instead of incurring latency and possibly seek time penalties to reach sectors

that are used as replacements for bad sectors (spare sectors), the FeRAM could be used for instant access sectors. Since a great number of sectors are dedicated for possible use as spare sectors, fewer spare sectors on the rotating media would be needed. The disk's spare sectors no longer have to be ve...