Fast Recovery; Protection (Shield); Figure 3.5 Fast Recovery - Fujitsu ETERNUS DX500 S3 Overview

Chapter 3 Basic Functions
3.1 Data Protection
3.1.5

Fast Recovery

This function recovers data quickly by relocating data in the failed drive to the other remaining drives when a
drive error is detected.
A RAID level (RAID6-FR) that preserves reserved areas equivalent to hot spares in a RAID group is used.

Figure 3.5 Fast Recovery

RAID6-FR (No redundancy)
RAID6-FR (Redundant)
3.1.6

Protection (Shield)

The Protection (Shield) function diagnoses temporary drive errors. A drive can continue to be used if it is de-
termined to be normal. The target drive temporarily changes to diagnosis status when drive errors are detec-
ted by the Disk Drive Patrol function or error notifications.
For a drive that configures a RAID group, data is moved to a hot spare by a rebuild or redundant copy before
the drive is diagnosed.
For a drive that is disconnected from a RAID group, whether the drive has a permanent error or a temporary
error is determined. The drive can be used again if it is determined that the drive has only a temporary error.
The target drives for the Protection (Shield) function are SAS disks and Nearline SAS disks (including self en-
crypting disks) that are registered in RAID groups or as hot spares. Note that the Protection (Shield) function
is not available for SSDs and unused drives.
High Speed Rebuilding
(Creating data and writing to the FHS area simultaneously)
Failure
RAID6-FR ((3D+2P) × 2 + 1HS)
Disconnect
RAID6-FR ((3D+2P) × 2)
FUJITSU Storage ETERNUS DX500 S3/DX600 S3 Disk storage system Overview
Copyright 2015 FUJITSU LIMITED
A failed drive is disconnected from the
ETERNUS DX.
Data is created from the redundant data
in normal drives and written to reserved
space (FHS) in RAID6-FR.
Failed drive
35
: Redundant data for area A
of the failed drive
: Redundant data for area B
of the failed drive
: Fast recovery Hot Spare (FHS)
P3AM-7702-14ENZ0