Chapter 3. IBM System Storage DS3500 Storage System planning tasks 71
Draft Document for Review March 28, 2011 12:24 pm 7914DS3KPlanning_090710.fm
Some points that may play an important part with premium features and should be
considered are the following:
Which premium features will you need
What additional resources will they require
Additional configuration needs
Amount of free space to support
Retention of copies needed
Automated or manual copies
Disaster recovery or backup operation needs
Then document the needs and requirements to support all the features being implemented.
Many of these premium features are purely to enable special capabilities within the DS3500;
however, features like the Copy Services can require additional resources to be able to
implement them and need to be considered when planning and implementing your
environment.
3.4.1 FlashCopy
A FlashCopy logical drive is a point-in-time image of a logical drive. It is the logical equivalent
of a complete physical copy, but you can create it much more quickly than a physical copy.
Additionally, it requires less disk space. In DS3500 Storage Manager, the logical drive from
which you are basing the FlashCopy, called the base logical drive, must be a standard logical
drive in the storage server. Typically, you create a FlashCopy so that an application (for
example, an application to take backups) can access the FlashCopy and read the data while
the base logical drive remains online and user-accessible. The DS3500 can have up to eight
FlashCopy volumes.
Plan carefully with regard to the space available to make a FlashCopy of a logical drive even
though FlashCopy takes only a small amount of space compared to the base image.
3.4.2 VolumeCopy
The VolumeCopy feature is a firmware-based mechanism for replicating logical drive data
within a storage subsystem. This feature is designed as a system management tool for tasks,
such as relocating data to other drives for hardware upgrades or performance management,
data backup, and restoring snapshot logical drive data.
A VolumeCopy creates a complete physical replication of one logical drive (source) to another
(target) within the same storage subsystem. The target logical drive is an exact copy or clone
of the source logical drive. VolumeCopy can be used to clone logical drives to other arrays
inside the DS3500 Storage System.
The VolumeCopy premium feature must be enabled by purchasing a Feature Key. For efficient
use of VolumeCopy, FlashCopy must be installed as well.
3.4.3 Enhanced Remote Mirroring
The Enhanced Remote Mirroring (ERM) option is used for online, real-time replication of data
between storage subsystems over a remote distance. ERM mirrors by creating a full logical
drive image on a secondary of the logical drive that is being mirrored from the primary. The
DS3500 can have up to eight mirrored pair relationships. The DS3500 can mirror to another
DS3500 or another member of the IBM Midrange DS Storage System family running 7.70.xx
code or higher. At the current time these are the only supported configurations.
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