Disks; Host Interface - Fujitsu Eternus DX60 User Manual

Chapter 1 Overview
1.2 Configuration
1.2.5

Disks

Three kinds of drives can be installed in the device: SAS disks, Nearline SAS disks, and SSDs.
Each is suitable for the following usage cases:
• SAS Disk
SAS disks are highly-performance/high-reliability disks for enterprise use. SAS disks support
24/7/365 operations and are used to store high performance databases and other frequently
accessed data.
2.5" SAS disks take less space, consume less electrical power, and are lighter than 3.5" SAS
disks.
• Nearline SAS Disk
Nearline SAS disks are high capacity / cost effective disks for data backup and archive use.
Nearline SAS disks can store information that requires a lower access rate at a still
reasonable speed more cost effectively than the SAS disks.
• SSD (Solid-State Drive)
SSDs are highly-performance/high-reliability drives for enterprise use. SSDs support 24/7/
365 operations and are used to store high performance databases and other frequently
accessed data. SSDs use flash memory as their storage media and provide better random
access performance than SAS and Nearline SAS hard disks. Containing no motors or other
moving parts, SSDs are highly resistant to impact and have low power consumption require-
ments.
2.5" SSDs take less space and are lighter than 3.5" SSDs.
1.2.6

Host Interface

The ETERNUS DX60/DX80 supports three types of host interfaces: the Fibre Channel interface,
the iSCSI interface, and the SAS interface. The ETERNUS DX90 supports the Fibre Channel
interface.
• Fibre Channel interface
Fibre Channel supports two connection topologies, Arbitrated Loop and Fabric.
Maximum transfer speed is 4Gbit/s for the ETERNUS DX60, 8Gbit/s or 4Gbit/s for the
ETERNUS DX80, and 8Gbit/s for the ETERNUS DX90.
Fibre Channel is commonly used for database servers. A fabric connection via an FC switch
will allow a large number of high-performance hosts to connect to a single port if required.
• iSCSI interface
iSCSI is a communication protocol which transfers SCSI commands within IP packets over
Ethernet, and has a maximum transfer speed of 1Gbit/s.
Since iSCSI can be installed at lower cost than Fibre Channel, it is commonly used by divi-
sions of large companies and by small-and-medium-sized companies.
In order to secure iSCSI performance, it is recommended that the iSCSI network be physi-
cally separated from other typical purpose networks such as those used for Internet access
and file transfer.
• SAS interface
SAS (Serial Attached SCSI) is a serial transfer host interface that is as reliable as the normal
(parallel) SCSI interface, but has a higher maximum transfer speed of 3Gbit/s.
SAS is used to connect servers and DAS (Direct Attached Storage) devices and, while provid-
ing less expandability than a SAN connection, is still suitable for small-sized systems.
ETERNUS DX60/DX80/DX90 Disk storage system User Guide
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