IBM System Storage DS4000, Hardware Manual

Page: 34 / 566

16
IBM Midrange System Storage Hardware Guide
2.1 Full Disk Encryption capable disk drive modules (DDM)
Disk Security is a new feature introduced with the DS5000 that complements the newly
available Full Disk Encryption (FDE) drives. It is supported by the latest level of DS5000
firmware (Version 7.60) and Storage Manager V10.60. This new feature can add a greater
level of security to data that resides on disk.
The Full Disk Encryption (FDE) disk is used in conjunction with IBM Disk Encryption Storage
Manager on the DS5000 storage subsystem. IBM Disk Encryption Storage Manager will
generate encryption and decryption keys that are used to lock each FDE drive so that all data
that resides on a disk is fully encrypted.
See Chapter 5, “Disk Security with Full Disk Encryption drives” on page 259 for details about
how FDE works and how to set it up.
2.2 Solid State Drive (SSD) module
The need for higher IOPS in enterprise storage led to a new storage type known as Solid
State Drive (SSD). SSDs have existed for some time, and were built in the past by using
volatile DRAM memory that was supplemented with battery backup. However, these were
enormously expensive and were often up to 1,000 times the cost of a high-performance disk
drive with an equivalent capacity.
Some applications require very high IOPS rates, and there are specific military or industrial
use cases that benefit from insensitivity to shock and vibration. But the vast majority of
applications cannot justify the extra cost, so SSDs have remained a rarity.
A new storage device type based on non-volatile flash memory is now available for enterprise
workloads that require high IOPS. Flash memory is less than 10 percent of the cost of DRAM,
and expected innovations should lower the cost by another order of magnitude in the next
2-3 years. By itself, however, flash memory is too slow to perform WRITE operations and has
an unacceptably short life. Clever engineering has been applied to use flash memory in
combination with DRAM and embedded software to create a device for enterprise
applications, one that is interface and function compatible with an HDD, but has substantially
higher IOPS performance. These devices made their appearance in 2008, and will be widely
available as optional devices in disk arrays. Flash-based SSDs are still more costly than
HDDs of equivalent capacity, but for high IOPS workloads, they can cost less.
The availability of a new type of storage device raises questions, including:
򐂰
What is the right use of the new devices?
򐂰 Are additional changes to the server, storage, and software stack required to see the full
value at the application level?
򐂰
How do we place the right data on these (expensive) devices at the right time to achieve
performance objectives without creating an undue burden of management?
IBM DS5000 offers a 76 GB SSD drive running on 4 Gbps Fibre Channel (FC) that is
compatible with the EXP5000.
You can read more about SSD drives in Appendix C, “Solid State Drives on the IBM System
Storage DS5000 series” on page 527.