Copy Services For System Z And S/390 Hosts; Consistency Groups - IBM DS8000 User Manual

With FCP, a single fibre-channel link between two ports enables bi-directional
remote mirror and copy operations. This means that it is possible to send and
receive data in both directions simultaneously. For example, one link can have a
path that is established in one direction and then have another path that is
established in another direction at the same time, on the same physical path.
While a FCP interface can accommodate simultaneous data transfers, it does have
limited bandwidth. To distribute workload evenly to all available paths, the storage
unit monitors the overall workload on each port and selects paths that are
determined by the size of the data transfer, the available bandwidth available on
each FCP port, and the number of data transfers, currently processing on each
port. Selecting paths in this manner ensures good response time and overall system
throughput.

Copy Services for System z and S/390 hosts

Copy Services functions are also supported in a System z or S/390 environment.
These functions allow you to create a point-in-time copy or to mirror data at your
remote or recovery site as applications make changes to the source volumes at
your production site.
Copy Services for System z and S/390 hosts includes z/OS Global Mirror.
z/OS Global Mirror
z/OS Global Mirror (previously known as Extended Remote Copy or XRC)
provides a long-distance remote copy solution across two sites for open systems
and System z data using asynchronous technology.
DS8000 storage complexes support the z/OS Global Mirror function only on
System z hosts. The Global Mirror function mirrors data on the storage unit to a
remote location for disaster recovery. It protects data consistency across all volumes
that you have defined for mirroring. The volumes can reside on several different
storage units. The z/OS Global Mirror function can mirror the volumes over
several thousand kilometers from the source site to the target recovery site.
With Global Mirror, you can suspend or resume service during an outage. You do
not have to end your current data-copy session. You can suspend the session, and
then restart it. Only data that changed during the outage must be synchronized
again between the copies.
z/OS Metro/Global Mirror
z/OS Metro/Global Mirror is an optional function that is available with the remote
mirror and copy feature for System z hosts and is supported on the DS8000.
The mirroring capability of z/OS Metro/Global Mirror uses Global Mirror to
mirror data at a production site to a location that is a long distance away. This
function also uses Metro Mirror to mirror data from the same primary devices at
the production site to a location within a metropolitan area. The z/OS
Metro/Global Mirror function enables a 3-site high availability and disaster
recovery solution for even greater protection from unplanned outages.

Consistency groups

Consistency groups are used for controlling error situations and for maintaining
data consistency at a recovery site.
130
DS8000 User's Guide