IBM DS8700, Introduction And Planning Manual

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To avoid this situation, the recovery commands you issue from the DS CLI should
be limited to 200 TB of configured volume size recovered in a single command. In
addition, issue the recovery commands serially. In a Tivoli Productivity Center for
Replication (TPC-R) configuration, the timeout value of the recovery commands
might need to be increased. In a Geographically Dispersed Parallel Sysplex (GDPS)
environment (managing open systems devices), the overall time allowed for the
recovery process might also need to be increased. Contact TPC-R or GDPS support
personnel to increase timeout values in your environments.
Thin provisioned volumes in open-system environments are supported for Copy
Services functions such as FlashCopy, Metro Mirror, Global Mirror, and Metro
Global Mirror. In a Metro Mirror relationship, the A and B volumes must be extent
space efficient (ESE) volumes. In a Global Mirror relationship, the Global Copy A
and B volumes must also be ESE volumes. The FlashCopy target volume (Volume
C) can be an ESE volume, target space efficient (TSE) volume, or standard volume.
Disaster recovery using Copy Services
One of the main reasons for using Copy Services functions is to prepare for a
possible disaster by backing up, copying, and mirroring your data both at the local
(production) and remote sites.
Having a disaster recovery plan can ensure that critical data is recoverable at the
time of a disaster. Because most disasters are unplanned, your disaster recovery
plan must provide a way that allows you to recover your applications quickly, and
more importantly, to access your data. Consistent data to the same point-in-time
across all storage units is vital before you can recover your data at a backup
(normally your remote) site.
Most users use a combination of remote mirror and copy and point-in-time copy
(FlashCopy) features to form a comprehensive enterprise solution for disaster
recovery. In an event of a planned event or unplanned disaster, you can use
failover and failback modes as part of your recovery solution. Failover and failback
modes help to reduce the time that is required to synchronize remote mirror and
copy volumes after you switch between the local (or production) and the
intermediate or remote sites during planned and unplanned outages. Although
failover transmits no data, it changes the status of a device, and the status of the
secondary volume changes to a suspended primary volume. The Failback
command transmits data and can go in either direction depending on which device
the Failback command is issued to.
Recovery procedures that include failover and failback modes use remote mirror
and copy functions, such as Metro Mirror, Global Copy, Global Mirror,
Metro/Global Mirror, and FlashCopy.
Note: See the IBM System Storage DS8000 Command-Line Interface User's Guide for
specific disaster recovery tasks.
Data consistency can be achieved using the following methods:
Manually using external software (without Global Mirror)
If you use Metro Mirror, Global Copy, and FlashCopy functions to create a
consistent and restartable copy at your recovery site, you must do a
manual and periodic suspend operation at your local site. This means
using
freeze and run commands together with external automated software
and then using the FlashCopy function to make a consistent copy of your
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Introduction and Planning Guide