Computer Drive User Manual

6 IBM System Storage DS6000 Series: Copy Services with IBM System z
Global Mirror (Asynchronous PPRC)
Global Mirror provides a long-distance remote copy feature across two sites using
asynchronous technology. This solution is based on the existing Global Copy and FlashCopy.
With Global Mirror, the data that the host writes to the Storage Unit at the local site is
asynchronously shadowed to the Storage Unit at the remote site. A consistent copy of the
data is automatically maintained on the Storage Unit at the remote site.
Global Mirror operations provide the benefit of supporting operations over virtually unlimited
distances between the local and remote sites, restricted only by the capabilities of the
network and the channel extension technology. It can also provide a consistent and
restartable copy of the data at the remote site, created with minimal impact to applications at
the local site.
The ability to maintain an efficient synchronization of the local and remote sites with support
for failover and failback modes helps to reduce the time that is required to switch back to the
local site after a planned or unplanned outage.
1.1.3 Optional Copy Services function for z/OS
The following functions are only available for z/OS environments with restrictions for where
they can be employed.
z/OS Global Mirror RMZ (formerly XRC)
DS6000 storage servers support z/OS Global Mirror only as a secondary storage server. You
cannot use a DS6000 as a primary storage server for z/OS Global Mirror.
The z/OS 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 z/OS Global Mirror, you can suspend or resume service during an
outage. You do not have to terminate your current data-copy session. You can suspend the
session, then restart it. Only data that changed during the outage must be re-synchronized
between the copies.
z/OS Global Mirror and Metro Mirror across 3 sites
This mirroring capability uses z/OS Global Mirror to mirror primary site data to a location that
is a long distance away and also uses Metro Mirror to mirror primary site data to a location
within the metropolitan area. This enables a z/OS 3-site high availability and disaster
recovery solution for even greater protection from unplanned outages. To use it, you must
purchase both of the following functions:
򐂰 Remote Mirror for z/OS (2244 Model RMZ for DS8000 Series) on primary site
򐂰 Remote Mirror and Copy function (2244 Model RMC for DS8000 Series or Machine Type
1750 feature code #5300 RMC for the DS6000 Series) for the primary Storage Unit and
secondary Storage Units at the alternate metropolitan site
Restriction: The XRC and 3-site z/OS Global Mirror environments are supported on
DS6000 Series only as secondary servers at remote sites. They only require standard
DS6000 Copy Services licenses for RMC for the appropriate storage level in a CKD
environment.