Specifications

ES/OL
Evaluator Series On-Line™
Storage Systems
Product Analysis
May, 2011
Page 15 of 30
Analysis of Fujitsu ETERNUS DX400 S2
Models DX410 and DX440
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Battery Backup
For ETERNUS DX410 S2 and DX440 S2, the battery backup maintains power for the controller and SSD on
the controller. In the event of a power failure, write cache data is saved on the SSD on the controller.
Parity
The PCI and PCI-Express busses have parity generating and checking circuitry that verify hardware integrity
for data transfers at the time that they are placed onto and taken off of the busses.
Error Checking and Correction (ECC)
The cache memory on each controller module uses ECC to detect all single and double bit errors and correct
single bit errors.
BlockGUARD
The earlier explanation of the data assurance by appending check characters onto every data block is part the
error detection system.
Hot Spares
Using hot spare disks is a configuration option. The operation of handling hot spares is as described in the
RAID Groups section of this document. After a failed drive is replaced, the data will be copied to the replaced
drive and the original spare returned to spare status.
RAID6
With the use of dual parity drives in a RAID6 configuration, the subsystem is better protected in the event of a
double disk failure (two disk drives fail concurrently.) RAID6 can be used with any type of drives within the
ETERNUS systems.
Concurrent Maintenance
A modular architecture is based on modules being able to be taken out of service while others take over the
workload. The ETERNUS DX400 S2 systems operate in a mode where some components can be replaced
without failing over to another controller while others require a failover to occur for service. Fujitsu states the
following components can have concurrent maintenance to provide access assurance.
• Array Controller, contains – Controllers, cache and channel adapters
• Power Supplies
• Cooling Fans
• Disks
Concurrent Firmware Updates
Firmware updates in the ETERNUS DX400 S2 systems is accomplished by the following operation:
1. Failing over LUN access from the primary controller to the secondary controller
2. Copying the firmware to the controllers flash ROM