HP StorageWorks XP Remote Web Console Software - Manual (Page 134)

134 TrueCopy for the XP128/XP1024/XP10000/XP12000
• RCU options: Incident of RCU, PPRC Support, Service SIM of Remote Copy, and FREEZE Option (see
” Registering an RCU (Add RCU) ” on page 81).
• TC390A offloading timer asynchronous option (see ” Asynchronous Copy Option ” on page 102)
and TC390A copy pending timeout group option (see ” Adding Consistency Groups (Add CT
Group) ” on page 99). The copy pending timeout group option can be used to limit the time
duration during which updates may be lost.
• TC390A Error Level pair option and M-VOL Fence Level pair option for TC390 Synchronous pairs
(see ” Creating TrueCopy Volume Pairs (Add Pair) ” on page 115).
4. Establish file and database recovery procedures. These procedures should already be established for
recovering volumes that are inaccessible due to control unit failure.
5. Install and configure error reporting communications (ERC) between the main and remote sites. ERC is
essential if you use the M-VOL fence level setting of R-VOL Status or Never for any TC390 volume pairs.
6. Configure the primary host system to use the IEA494I message as a trigger for automation rather than
the IEA491E message. The IEA491E message is reported to only one host, whereas the IEA494I
message is reported to all attached MVS hosts each time the M-VOL pair status changes. For more
information on the IEA494I and IEA491E system console messages, see ” IEA494I and IEA491E
Console Messages ” on page 164.
Considering the M-VOL Fence Level Setting
The M-VOL fence level setting (see ” Creating TrueCopy Volume Pairs (Add Pair) ” on page 115) for each
TC390 Synchronous volume pair determines whether the M-VOL will be fenced when TC390 remote copy
operations fail. The following table summarizes the effect of the fence level setting on a TC390
Synchronous M-VOL.
NOTE: The M-VOL fence level setting does not apply to TC390A pairs. The TC390A M-VOL is never
fenced due to suspension of the pair.
R-VOL Data (CRIT=Y(ALL)). When this fence level setting is selected, the M-VOL will be fenced if an update
copy operation fails. This M-VOL fence level setting ensures that the R-VOL remains identical to the M-VOL
after the TC390 volume pair is synchronized, but makes the M-VOL inaccessible to applications for
updates whenever TC390 remote copy operations fail. This setting should be considered for the most
critical volumes for disaster recovery. This setting will reduce the amount of time required to analyze the
currency of the R-VOL during disaster recovery efforts. This setting is also designed for applications that
can continue to operate with another device pair (for example, IMS logger dual write log files).
R-VOL Status (CRIT=Y(PATHS)). When this fence level is selected, the M-VOL is fenced only if the MCU is
not able to change the R-VOL pair status to suspended. If the MCU successfully changes the R-VOL pair
status to suspended, subsequent write I/O operations to the M-VOL will be accepted and the MCU will
keep track of updates to the M-VOL. This allows the volume pair to be resumed quickly using the resync
Table 22 Fence level setting on a TrueCopy M-VOL
Type of Failure Fence Level Setting
R-VOL Data
(CRIT=Y(ALL))
R-VOL Status
(CRIT=Y(PATHS))
Never
(CRIT=NO)
The update copy operation
failed and the MCU was able
to change the status of the
R-VOL to
suspended .
Write I/O operations
to the M-VOL will be:
REJECTED Accepted Accepted
The update copy operation
failed and the MCU was
NOT able to change the
status of the R-VOL to
suspended .
Write I/O operations
to the M-VOL will be:
REJECTED REJECTED Accepted