Browse Prior Art Database

Method and Means of Providing Automatic Synchronization on RAID 5 Drives

IP.com Disclosure Number: IPCOM000123596D
Original Publication Date: 1999-Feb-01
Included in the Prior Art Database: 2005-Apr-05
Document File: 1 page(s) / 49K

Publishing Venue

IBM

Related People

Lee, T: AUTHOR [+3]

Abstract

This disclosure describes a function that provides a means to perform synchronization of RAID 5 logical arrays without any user intervention. This operation is performed concurrently as a background task, thus making the logical array usable at the instant of its creation. Currently, a user would have to manually synchronize a RAID 5 drive after creating it. Also, this being a foreground task, would take up a lot of time before completion and the drive becoming usable (the time for synchronization, increasing with the size of the drive). A redundant (R5) drive has to be synchronized in order to make all the data units (stripes) consistent.

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Method and Means of Providing Automatic Synchronization on RAID 5
Drives

   This disclosure describes a function that provides a means
to perform synchronization of RAID 5 logical arrays without any user
intervention.  This operation is performed concurrently as a
background task, thus making the logical array usable at the instant
of its creation.  Currently, a user would have to manually
synchronize a RAID 5 drive after creating it.  Also, this being a
foreground task, would take up a lot of time before completion and
the drive becoming usable (the time for synchronization, increasing
with the size of the drive).  A redundant (R5) drive has to be
synchronized in order to make all the data units (stripes)
consistent.

   The function is implemented as explained below, * Any
ServeRAID host application that provides a means of creating a RAID 5
logical drive, will send a CHK_CONSISTENCY command to the
controller, if the logical drive creation was successful.  * The
controller, will route the command to the Check Consistency Engine in
the firmware, where it is validated and the synchronization started
if feasible or is registered to be started whenever feasible.  (The
feasibility is determined by factors such as, if any rebuild or
logical drive migration or another CHK_CONSISTENCY is in progress.
This happens because such operations are carried out per logical
drive basis) * Synchronization is performed on subsequent stripes, 4
stripes at a time.  All the relevant da...