Dell EMC Solutions Enabler 9.2 SRDF Family CLI User Guide

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SRDF pair states and links

NOTE:Before you begin SRDF control operations, you must understand how SRDF devices and links work together to secure data within SRDF configurations.

NOTE:

The following content assumes you understand SRDF devices, including R1, R11, R2, and R21. For a detailed description of SRDF devices, refer to the EMC VMAX3 Family Product Guide for VMAX 100K, VMAX 200K, VMAX 400K with HYPERMAX OS, Dell EMC VMAX All Flash Product Guide for VMAX 250F, 450F, 850F, 950F with HYPERMAX OS and Dell PowerMax Family Product Guide.

An SRDF pair state encompasses:

SRDF device state on the source (R1) device
SRDF device state on the target (R2) device
The number of tracks owed between the R1 and R2 devices (invalid tracks)
Whether the device pair is part of an SRDF/Metro configuration, and
The SRDF link state between the R1 and R2 devices
NOTE:
See Invalid tracks in SRDF pairs.
The following image shows states SRDF devices and links can report for SRDF/A, SRDF/S and SRDF/Metro configurations.

Figure 1. SRDF device and link states

Table 1. SRDF device and link states
NR	Not Ready. Reads and writes are both disabled.
RW	Ready. Enabled for both reads and writes.
WD	Write Disabled. Enabled for reads but not writes.
NA	Not Available. Unable to report on correct state.
ActiveActive	R1 SRDF state is Ready. SRDF link state is Ready. R2 SRDF state is Ready. R1 and R2 invalid tracks are 0.
ActiveBias	R1 SRDF state is Ready. SRDF link state is Ready. R2 SRDF state is Ready. R1 and R2 invalid tracks are 0.