Takeover-Switch Function - Hitachi VSP F1500 User And Reference Manual

Takeover-switch function

The control scripts activated by HA software are used by all nodes of a cluster
in exactly the same manner so they have no discrimination between primary
and secondary pair volumes (they just know the near and far disk in a pair).
Thus, the takeover command, when activated by a control script, must check
the combination of attributes of volumes possessed by the local and remote
nodes and determine the proper takeover action. The table below shows the
takeover actions.
Table 6-1 Near/Local and Far/Remote Volume Attributes and Takeover
Local node (Takeover node)
Volume
attribute
SMPL
P-VOL
(primary)
S-VOL
(secondary
)
Notes:
1 No action needed to allow local writes.
.
2 Required to allow local writes.
.
6-12
Fence and status
-
Fence == Data or
Status && pair
status == PSUE or
PDUB or MINAP ==
0
Others
Status == SSWS
(After
SVOL_SSUStakeove
r)
Other than SSWS
Data replication operations with CCI
Command Control Interface User and Reference Guide
Actions
Remote node
Volume
P-VOL status
attribute
SMPL -
P-VOL -
S-VOL -
Unknown -
SMPL -
P-VOL -
S-VOL -
Unknown -
SMPL -
P-VOL -
S-VOL -
Unknown -
- -
SMPL -
P-VOL PAIR or PFUL
Others
S-VOL -
Unknown -
Takeover action
Reject
1
Nop-takeover
Unconformable
Reject
Reject
Unconformable
2
PVOL-Takeover
2
PVOL-Takeover
Reject
Unconformable
1
Nop-takeover
1
Nop-takeover
1
Nop-takeover
Unconformable
2
Swap-takeover
2
SVOL-takeover
Unconformable
2
SVOL-takeover