Chapter 3 Functions; Data Protection; Data Block Guard; Figure 3.1 Data Block Guard - Fujitsu ETERNUS DX60 S3 Overview Manual

Chapter 3
Functions
This chapter explains the available functions for the ETERNUS DX.
3.1

Data Protection

The ETERNUS DX has functions to securely protect user data.
3.1.1

Data Block Guard

When data is written from the server, the Data Block Guard function adds eight bytes check codes to each
block (every 512 bytes) of the data and verifies the data at multiple checkpoints to ensure data consistency.
This function can detect a data error when data is destroyed or data corruption occurs. When data is read
from the server, the check codes are confirmed and then removed, ensuring that data consistency is verified
in the whole storage system.

Figure 3.1 Data Block Guard

User data
A0
A0 CC A1
CC: Check code
Written data
A0 CC A1
1. The check codes are added
2. The check codes are confirmed
3. The check codes are confirmed and removed
Write
A1 A2
1
CC A2 CC
Cache memory
2
CC A2 CC
FUJITSU Storage ETERNUS DX60 S3 Disk storage system Overview
Copyright 2014 FUJITSU LIMITED
Read
3
A0
Controller
2
25
User data
A0 A1 A2
CC A1 CC A2 CC
P3AM-8972-01ENZ0