Data Protection; Data Block Guard; Figure 3.1 Data Block Guard - Fujitsu ETERNUS DX500 S3 Overview

Chapter 3 Basic Functions
3.1

Data Protection

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
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
In addition, the T10-DIF function is supported. T10-DIF is a function that adds a check code to data that is to
be transferred between the Oracle Linux server and the ETERNUS DX, and ensures data integrity at the SCSI
level.
The server generates a check code for the user data in the host bus adapter (HBA), and verifies the check
code when reading data in order to ensure data integrity.
The ETERNUS DX double-checks data by using the data block guard function and by using the supported T10-
DIF to improve reliability.
Data is protected at the SCSI level on the path to the server. Therefore, data integrity can be ensured even if
data is corrupted during a check code reassignment.
By linking the Data Integrity Extensions (DIX) function of Oracle DB, data integrity can be ensured in the
entire system including the server.
Write
A1 A2
1
CC A2 CC
CC: Check code
Cache memory
2
CC A2 CC
FUJITSU Storage ETERNUS DX500 S3/DX600 S3 Disk storage system Overview
Copyright 2015 FUJITSU LIMITED
Read
3
A0
Controller
2
32
User data
A0 A1 A2
CC A1 CC A2 CC
P3AM-7702-14ENZ0