Basic Functions; Data Protection; Data Block Guard; Figure 5 Data Block Guard - Fujitsu ETERNUS DX500 S3 Overview

3.

Basic Functions

The ETERNUS DX integrates block data (SAN area) and file data (NAS area).
The ETERNUS DX has functions such as the SAN function (supports block data access), the NAS function (supports
file data access), and basic functions that can be used without needing to recognize the SAN or the NAS.
This chapter explains the basic functions of the ETERNUS DX.
For more details about the functions that are used for a SAN connection, refer to
For more details about the functions that are used for a NAS connection, refer to

Data Protection

The ETERNUS DX has functions to securely protect user data.

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 func-
tion 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 5 Data Block Guard

User data
A0 A1
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.
Write
A2
1
CC A2 CC
Controller
CC: Check code
Cache memory
2
CC A2 CC
FUJITSU Storage ETERNUS DX500 S3/DX600 S3 Hybrid Storage Systems Overview
Copyright 2019 FUJITSU LIMITED
Read
User data
A0
3
A0 CC A1
2
29
"4. SAN Functions" (page
"5. NAS Functions" (page
A1 A2
CC A2 CC
P3AM-7702-29ENZ0
50).
63).