6 IBM TotalStorage DS6000 Series: Performance Monitoring and Tuning
because it does not need to manage parity. However, with half of the DDMs in the group used
for data and the other half used to mirror that data, RAID 10 disk groups have less capacity
than RAID 5 disk groups.
1.3.2 Resiliency
The DS6000 series has built in resiliency features that are not generally found in small
storage devices. The DS6000 series is designed and implemented with component
redundancy to help reduce and avoid many potential single points of failure.
Within a DS6000 series controller unit, there are redundant RAID controller cards, power
supplies, fans, Fibre Channel switches, and Battery Backup Units (BBUs).
There are four paths to each disk drive. Using Predictive Failure Analysis®, the DS6000 can
identify a failing drive and replace it with a spare drive without customer interaction.
1.3.3 Copy Services
Copy Services is a collection of functions that provide Disaster Recovery, data migration, and
data duplication functions. Copy Services run on the DS6000 server enclosure and they
support open systems and zSeries environments.
Copy Services has four interfaces; a Web-based interface (DS Storage Manager), a
command-line interface (DS CLI), an application programming interface (DS Open API), and
host I/O commands from zSeries servers.
Point-in-time copy feature
IBM TotalStorage FlashCopy, a key member of the IBM TotalStorage Resiliency Family is
designed to offer DS6000 users industry leading point-in-time copy flexibility. Offering high
performance full and NOCOPY (copy on first write) capabilities, FlashCopy supports many
advanced capabilities including:
Data Set FlashCopy
Data Set FlashCopy allows a FlashCopy of a data set in a zSeries environment.
Multiple Relationship FlashCopy
Multiple Relationship FlashCopy allows a source to have FlashCopy relationships with
multiple targets simultaneously. This flexibility allows you to initiate up to 12 FlashCopy
establishes on a given logical unit number (LUN), volume, or data set, without needing to first
wait for or cause previous relationships to end.
Incremental FlashCopy
Incremental FlashCopy provides the capability to refresh a LUN or volume involved in a
FlashCopy relationship. When a subsequent FlashCopy establish is initiated, only the data
required to bring the target current to the source's newly established point-in-time is copied.
The direction of the
refresh can also be reversed, in which case the LUN or volume previously
defined as the target becomes the source for the LUN or volume previously defined as the
source (and is now the target).
FlashCopy to a remote mirror primary
This capability lets you establish a FlashCopy relationship where the target is also a remote
mirror primary volume. This enables you to create full or incremental point-in-time copies at a
local site and then use remote mirroring commands to copy the data to the remote site.

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