SRDF consistency

[DWGriff1]

looking at the output from "symrdf -g CWVDYN1 query -rdfa", what does the column C in MODES mean ?
What's the difference between it and the state column

Source (R1) View Target (R2) View MODES
-------------------------------- ------------------------ ----- ------------
ST LI ST
Standard A N A
Logical T R1 Inv R2 Inv K T R1 Inv R2 Inv RDF Pair
Device Dev E Tracks Tracks S Dev E Tracks Tracks MDAC STATE
-------------------------------- -- ------------------------ ----- ------------

DEV001 09DA RW 0 0 RW 051D WD 0 0 A... Consistent
DEV002 0A52 RW 0 0 RW 0560 WD 0 0 A... Consistent
DEV003 0A58 RW 0 0 RW 0566 WD 0 0 A... Consistent
DEV004 0A5E RW 0 0 RW 056C WD 0 0 A... Consistent
DEV005 0A9A RW 0 0 RW 0388 WD 0 0 A... Consistent
DEV006 0AD6 RW 0 0 RW 03C4 WD 0 0 A... Consistent
DEV007 0B12 RW 0 0 RW 0400 WD 0 0 A... Consistent
DEV008 0A74 RW 0 0 RW 0573 WD 0 0 A... Consistent

Total -------- -------- -------- --------
Track(s) 0 0 0 0
MB(s) 0.0 0.0 0.0 0.0

Legend for MODES:

M(ode of Operation): A = Async, S = Sync, E = Semi-sync, C = Adaptive Copy
D(omino) : X = Enabled, . = Disabled
A(daptive Copy) : D = Disk Mode, W = WP Mode, . = ACp off
C(onsistency State): X = Enabled, . = Disabled, - = N/A

[xe2sdc · Accepted solution]

When a RDFG is working in SRFD/A mode, you can't put a single device in a different state, you have to manage the group as a single thing. But what happens when a single pari have issues?? The default behaviour is to tolerate single drives with different status on the RDFG (again, only when it depends on a different issue).
What can you do to protect consistency of R2 devices ?? You can use "symrdf enable" command to disable tolerancy (hmm sounds tricky)
When you issue "symrdf enable" command against your CWVDYN1 DG you'll find nice X under the "C" column.

[DWGriff1]

So the X in the "C" column means consistency protection is enabled. This means if SRDF is unable to write to one of the R2 devices it will stop writing to all in the group. While the Consistant in the state column refers to a single device pair.

[xe2sdc]

Perfect.

[dkakljkml]

HI stefano ,

I have some issue understanding the use of symrdf enable in single session setup. I have one source and target connection to each other with Async mode . What scenario do you think with help me by enabling symrdf enable on the Async mode. I dont see any possibility of a single lun going bad in the Vmax world with thin pool . Can you help me to understand how enabling consistency with benefit