Dell PowerFlex 4.5.x Administration Guide

Remote protection

PowerFlex enables native asynchronous replication for PowerFlex storage-only and hyperconvered configurations. Remote protection is an optional feature which ensures data protection of the PowerFlex environment. It creates a remote copy of one volume from one cluster to another.

Replication is used to quickly and easily recover from a physical or logical disaster, to migrate data, to test data at a remote site, or to offload backup. The PowerFlex implementation is designed to allow a sub-minute RPO reducing the data-loss to minimal if there is disaster recovery. As with all other PowerFlex data services, replication is elastic, can scale online by adding or removing nodes, is flexible, and easy to manage. It enables instant test and failover operations.

When replicating between systems it is recommended to have the same storage pool type, disk capacity and type, and performance capabilities between the local and remote sites. While replication between medium granularity (MG) to fine granularity (FG) storage pools is fully supported, account for the performance characteristics of each storage pool. PowerFlex does not support replication of volumes mapped to NVMe hosts.

The following workflow summarizes setup of remote replication. See specific procedures for detailed steps.

1. Install the remote (target) PowerFlex system.
2. Extract a certificate on each PowerFlex system and copy it to its peer system.
3. Configure journal capacity. Journal capacity is a percentage of the total storage capacity. There are several factors that should be considered when defining it:
   • Journal capacity must be allocated to be able to add SDRs to the system.
   • Before configuring journal capacity, ensure that there is enough space in the storage pool.
   • The journal capacity depends on the change rate and Recovery Point Objective (RPO). Data writes are accumulated in the journal until half the RPO time has been reached, to ensure that data is not lost and a consistent copy is maintained between the volumes.
   • When the total storage capacity in the system increases, a small percentage is needed for the journal capacity.
   • As application workload increases, more journal capacity must be added, accordingly.
4. Ensure that SDRs are installed and added to the source and peer systems.
   • The SDR component is typically installed during installation of PowerFlex. It manages replication activity within the system, and between the source and target. Dell recommends installation of at least three SDRs per system, for failure or backup purposes. Within the system, the SDR channels the I/O writes from the host to the source journal. Simultaneously, it also sends the data to the SDS to be logged. As data accumulates in the source journal, the system decides when to close the journal (this is usually at half the RPO time) in order to be ready to transfer the data to the target journal. At the target site, the SDR is also responsible for applying the data from the target journal to the target volume.
5. Define peer (target) systems from the source side.
6. Create and activate replication consistency groups (RCGs).
   • An RCG is a set of volumes which must maintain a consistent copy on the remote (target) site where write order is maintained between volumes. This pair shares the same attributes.
   • The volumes to be replicated must be the same size on source and target systems. If the network is up, the systems should be connected.