Dell EMC Solutions Enabler 9.2 SRDF Family CLI User Guide

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SRDF modes in cascaded configurations with EDP

SRDF/Extended Distance Protection (EDP) enables you to designate an R21 device as a diskless device.

A diskless R21 device directly cascades data to the remote R2 disk device, streamlining the linkage and cost of storage at the middle site.

Table 1. SRDF modes for cascaded configurations with EDP
R1 -> Diskless R21	Diskless R21 -> R2
Synchronous Adaptive copy disk Adaptive copy write pending*	Asynchronous
Synchronous Adaptive copy disk Adaptive copy write pending*	Adaptive copy write pending*

*Adaptive copy write pending mode (acp_wp) is not supported when the R1 side of the RDF pair is on an array running HYPERMAX OS, and diskless R21 devices are not supported on arrays running HYPERMAX OS.