Figure 1-5
Process of data recovery at the primary site following a disaster
Standby host
Primary
LUN
Secondary storage
system
New remote replication
links
Production
host
Primary storage system
Secondary storage system
Standby host
The standby
host runs
services.
Remote replication
Production
host
Primary storage system
Secondary storage system
Standby host
The
production
host runs
services.
Primary site
Secondary site
Links restored
Recovers data
Production
host
Primary storage
system
Secondary
LUN
Primary
LUN
Primary
LUN
Secondary
LUN
1. The primary site recovers from the
disaster.
·
The primary storage system recovers
from the disaster. And the links
between storage systems are
restored.
·
After the links are restored, it is
need to perform a primary/secondary
switchover manually on the primary
site, to make the secondary LUN on
the secondary storage system
become the primary one.
2. The secondary site recovers data at the
primary site.
·
Synchronous: Perform synchronization
once to copy data on the primary LUN
to the secondary LUN.
·
Asynchronous: Perform
synchronization for multiple times
during idle hours to copy data on the
primary LUN to the secondary LUN.
·
Synchronous: Perform a
primary/secondary switchover to
restore the pre-disaster pair.
·
Asynchronous: Start synchronization
again to eliminate the difference
caused by host writes during the
previous synchronization. Then split
Pair to set the secondary LUN to be
writable and perform a
primary/secondary switchover to
restore the pre-disaster pair.
·
After recovered the pair, set the
secondary resource protection status
to read-only in the primary storage
system.
3. The primary site recovers services.
Secondary
LUN
Phases in
a
data
recovery process
NOTE
In asynchronous remote replication scenarios, the storage system performs data synchronization until
data differences between the primary and secondary LUNs are minimal. The storage system then stops
services and performs the final synchronization. This prevents data loss and minimizes downtime.
1.3.5 Functions of a Consistency Group
In medium- and large-sized database applications, data, logs, and modification information
are stored on different LUNs that have relationships with each other. If data on one of the
LUNs becomes unavailable, data on the other LUNs also becomes unavailable. Adding LUN
pairs to a consistency group ensures the availability of data on the LUNs. This section
compares storage systems running a consistency group with storage systems not running a
consistency group to show you how a consistency group ensures business continuity.
OceanStor V3 Series
Remote Replication Feature Guide for Block
1 Feature Description
Issue 06 (2018-01-30)
Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
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