Hitachi TAGMASTORE MK-90RD011-25 User Manual page 242

Notes:
1. NG = The takeover command is rejected, and the operation terminates abnormally.
2. Nop-Takeover = The takeover command is accepted, but no operation is performed.
3. Volumes not conform = The volumes are not in sync, and the takeover command
terminates abnormally.
4. Unknown = The remote node attribute is unknown and cannot be identified. The remote
node system is down or cannot communicate.
5. SSWS = Suspend for Swapping with SVOL side only. The SSWS state is displayed as SSUS
(SVOL_PSUS) by ALL commands except the " -fc " option of the pairdisplay command.
4.10.1.2 Swap-Takeover Function
When the P-VOL status of the remote node is PAIR and the S-VOL data is consistent, it is
possible to swap the primary and secondary volumes. The swap-takeover function is used by
the HA control script when a package is manually moved to an alternate data center while
all hardware is operational. Swap-takeover can be specified for a paired volume or a group.
The swap-takeover function internally executes the following commands to swap the primary
and secondary volumes:
1. Execute Suspend for Swapping for the local volume (S-VOL). If this step fails, swap-
takeover is disabled and an error is returned.
2. Execute Resync for Swapping for switch to the primary volume that the local volume
(S-VOL) is swapped as the NEW_PVOL and resynchronizes the NEW_SVOL based on the
NEW_PVOL. As for copy tracks, if the remote host is known, the command will use the
value of PVOL specified at paircreate time. If the remote host is unknown, the command
will use the default number of tracks (three). If this step fails, swap-takeover returns at
SVOL-SSUS-takeover, and the local volume (S-VOL) is maintained in SSUS(PSUS) state
which allows and keeps track of write I/Os using a bitmap for the S-VOL. This special
state is displayed as SSWS using the -fc option of the pairdisplay command.
Note: The swap-takeover function does not use SMPL or No Copy mode for swapping to
guarantee mirror consistence, and this is included as a function of SVOL-takeover.
Note for Hitachi TrueCopy Async: The CCI software on the S-VOL side will issue a Suspend
for Swapping to the S-VOL side RAID storage system. Non-transmitted data which remains in
the FIFO queue (sidefile) of the P-VOL will be copied to the S-VOL, and a Resync for
Swapping operation will be performed (after the copy process). The swap operation is
required to copy non-transmitted P-VOL data within a given timeout value (specified by the
-t <timeout> option).
224 Chapter 4 Performing CCI Operations