Disaster Recovery (DR) Solutions protect against failures of the local storage or database by keeping a remote, up-to-date copy of the data. This can be done by the database, using software like Oracle Data Guard, or by the storage, using storage replications such as Dell EMC SRDF/Metro. If a failure occurs that causes an interruption of operations to the local database, it will be failed over to the remote copy and continue operations from there.
SRDF/Metro provides higher database resiliency at short distances (up to approximately 100km), based on synchronous replication. To provide longer distance resiliency, SRDF asynchronous (SRDF/A) replication can be used.
SRDF/Metro Smart DR integrates SRDF/Metro and SRDF/A to allow both HA (provided by SRDF/Metro and Oracle Extended RAC) and DR (provided by SRDF/A). Previously, this solution required each of the SRDF/Metro storage systems to have its own SRDF/A remote copy of the data. With PowerMaxOS release of Q3 2020, SRDF/Metro Smart DR introduced the ability to combine the DR targets to a single copy of the data.
The two sides of an SRDF/Metro system are set to the active/active state as before, servicing both read and writes. Each side is also connected with SRDF/A to a third storage system farther away. Only one side of the SRDF/Metro storage systems, (called the ‘Master’), will actively transmit data to the DR site, while the secondary system will monitor and keep track of the updated data. In the event of a failure that causes the Master to drop connectivity to the DR site, the secondary system in the SRDF/Metro Smart DR will take over and start transmitting data to the DR site.
Figure 2. SRDF/Metro Smart DR Environment