IBM DS8880 Series, Introduction And Planning Manual

Page: 92 / 244

Table 28 provides a brief summary of the characteristics of the Copy Services
features that are available for the storage system.
Table 28. Comparison of features
Feature Description Advantages Considerations
Multiple Target PPRC Synchronous and
asynchronous
replication
Mirrors data from a
single primary site to
two secondary sites
simultaneously. Disaster recovery
scenarios depend on
support from
controlling software
such as
Geographically
Dispersed Parallel
Sysplex (GDPS) and
IBM Copy Services
Manager
Metro/Global Mirror Three-site, long
distance disaster
recovery replication A backup site is
maintained
regardless of which
one of the sites is
lost. Recovery point
objective (RPO)
might grow if
bandwidth capability
is exceeded.
Metro Mirror Synchronous data
copy at a distance No data loss, rapid
recovery time for
distances up to 300
km. Slight performance
impact.
Global Copy Continuous copy
without data
consistency Nearly unlimited
distance, suitable for
data migration, only
limited by network
and channel
extenders
capabilities. Copy is normally
fuzzy but can be
made consistent
through
synchronization.
Global Mirror Asynchronous copy Nearly unlimited
distance, scalable,
and low RPO. The
RPO is the time
needed to recover
from a disaster; that
is, the total system
downtime. RPO might grow
when link bandwidth
capability is
exceeded.
z/OS Global Mirror Asynchronous copy
controlled by IBM Z
host software Nearly unlimited
distance, highly
scalable, and very
low RPO. Additional host
server hardware and
software is required.
The RPO might grow
if bandwidth
capability is exceeded
or host performance
might be impacted.
I/O Priority Manager
The performance group attribute associates the logical volume with a performance
group object. Each performance group has an associated performance policy which
determines how the I/O Priority Manager processes I/O operations for the logical
volume.
80
DS8880 Introduction and Planning Guide