Browse Prior Art Database

Power drop protection in HDD

IP.com Disclosure Number: IPCOM000014331D
Original Publication Date: 2001-Jul-01
Included in the Prior Art Database: 2003-Jun-19
Document File: 2 page(s) / 63K

Publishing Venue

IBM

Abstract

This method solves the hard error problem caused by non intentional power off during

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Power drop protection in HDD

This method solves the hard error problem caused by non intentional power off during

write operation in Hard Disk Drive (HDD). There are two data loss happens by the

power drop during write operation, data loss transferred from the host to HDD and the

data split in sector as the write operation stops between the sector.

This method requires at least one sector size non volatile memory like MRAM and the

wrote operation stop sequence when the power drop happens. The sequence is shown

in the next flow chart.

V1

V2

              Time <V 1 : U nder the voltage spec <V 2 : U n-controlled operation range

Power Drop Protection in H D D

STA R T

V 1 D ETEC TED ?

N O

NO RM AL W IRTE

CO M PLETE W RITE TO C U R R EN T SEC TO R WRITE RESIDUAL DATA TO M RAM

N O

V 2 D ETEC TED ?

YES

STO P W R ITE

EN D

VO LTAG E SENSO R

When the power drop to V1 is detected by the voltage sensor, the sequence

starts. First, complete the current sector writing and the data stored in the

buffer is transferred to the nonvolatile area prepared by MRAM, and those

sector address not written to the disk are written in the predefined table in

MRAM. These operations should be completed before the power voltage

becomes V2.

The power on sequence checks the sector table inside MRAM whether power

drop sequence happened in the last power off sequence, and if the sector

address is written, the data in MRAM will be written to the disk. All the data

will be erased if the sector data are transferred...