SAP Landscape Management 3.0, Enterprise Edition

Multitier System Replication

To offer higher levels of availability you can link together multiple systems in a multitier system replication landscape.

After setting up a basic system replication scenario you add a third system to provide another level of redundancy.

In a multitier setup the primary system is always on tier 1, a tier 2 secondary has a primary system as its replication source and a tier 3 secondary has the tier 2 secondary as its replication source.

Takeover on tier 2 and failback to original 3 tier system setup

NoteThe following image contains links to more information.
If your primary system is not available, due to a disaster or planned downtime for example, and you have decided to fail over to the secondary system, you can perform a takeover on your secondary node. SAP Landscape Management stops all instances of other systems that are non productive SAP HANA systems. Once your original primary system is operational again after a disaster or planned downtime, for example, you can fail back to your original primary system. Tier 1 does not commit a transaction until it receives confirmation that the log has been persisted in tier 2. This mode guarantees immediate consistency between both systems, however, the transaction is delayed by the time it takes to transmit the data to and persist it in tier 2. Tier 2 sends redo log buffers to tier 3 asynchronously. Tier 2 commits a transaction when it has been written to the log file of tier 2 and sent to tier 3 through the network. It does not wait for confirmation from tier 3.

Takeover on tier 3 and failback to 2 tier system setup

NoteThe following image contains links to more information.
Tier 1 does not commit a transaction until it receives confirmation that the log has been persisted in tier 2. This mode guarantees immediate consistency between both systems, however, the transaction is delayed by the time it takes to transmit the data to and persist it in tier 2. Tier 2 sends redo log buffers to tier 3 asynchronously. Tier 2 commits a transaction when it has been written to the log file of tier 2 and sent to tier 3 through the network. It does not wait for confirmation from tier 3. If your primary and secondary system is not available, and you have decided to fail over to the third system, you can perform a takeover on your third node. SAP Landscape Management stops all instances of other systems that are non productive SAP HANA systems. Once your original primary system is operational again after a disaster or planned downtime, for example, you can fail back to your original primary system.