Write-back protection mode can offer a higher level of performance than write-through protection mode if the replication log resides on faster storage than primary storage. This is because write operations from protected VMs are marked complete upon receiving acknowledgement from the replication log alone. Writes to primary storage are asynchronous and do not hold back overall write performance. 

To ensure the integrity of data and a higher level of performance, it is recommended that write-back protection is used with SSD-based iSCSI LUN that is accessible by both DRVA and all ESXi hosts in the cluster. Furthermore, safeguards should be implemented, such as the use of mirrored RAID on the replication log to guard against any possible failure of the replication log. Write-back protection can also be done using VMDK storage; however, ISCSI LUN typically offers the highest level of performance.

Note: The Write-Back (iSCSI LUN) option in the drop-down menu will only appear when the protected domain is using an iSCSI replication store.