In partner group configurations, the loop split feature that was removed with 1.13 firmware is back, following an upgrade to 1.18 (T3) or 2.01 (T3+)

This affects the behavior of the .loop stat and the .disk linkstat u2d1-9 path 0. The loop split feature is enabled by default after the firmware upgrade. The system option to view this is .sys list which will show a new setting called .loop_split : auto.

To confirm that the loop1 is split out, do the following:

  .loop stat
  Loop 1: <1+> <2+>
  Loop 2: <1+2+>
            

Notice that loop 1 is split.

The behavior of this feature will be reflected in .loop linkstat u2d1-9 path 0 as ..

t3
.disk linkstat u2d1-9 path 0

DISK LINKFAIL LOSSSYNC LOSSSIG PROTOERR INVTXWORD INVCRC
--------------------------------------------------------
u2d1 Disk Link Status Failed
u2d2 Disk Link Status Failed
u2d3 Disk Link Status Failed
u2d4 Disk Link Status Failed
u2d5 Disk Link Status Failed
u2d6 Disk Link Status Failed
u2d7 Disk Link Status Failed
u2d8 Disk Link Status Failed
u2d9 Disk Link Status Failed

fail
            

On path 1 the behavior will remain consistent with older versions of firmware ..

.disk linkstat u2d1-9 path 1

DISK LINKFAIL LOSSSYNC LOSSSIG PROTOERR INVTXWORD INVCRC
--------------------------------------------------------
u2d1 0 0 0 0 20 0
u2d2 1 1 0 0 14 0
u2d3 1 13 0 0 144 0
u2d4 1 2 0 0 16 0
u2d5 0 1 0 0 14 0
u2d6 0 0 0 0 18 0
u2d7 1 1 0 0 14 0
u2d8 1 2 0 0 19 0
u2d9 1 3 0 0 98 0

pass
            

The loop split will cause spurious SVD Path failovers on u2d4-9 after reboot, when the loop splits, and during any time that the loop heals.