HP NonStop G-Series - Manual (Page 226)

Operations and Management
HP AutoSYNC User’s Guide—522580-016
A-14
Takeover Procedures
The =_AUTOSYNC_SYSDB DEFINE is class CATALOG and specifies a subvolume
for the SysDB tables. If this DEFINE is present when AUTOSYNC is started, it does
not look for the normal SysDB, but uses the one specified. Thus, it operates only with
MapDBs and monitor processes that are created under the specified SysDB.
A typical =_AUTOSYNC_SYSDB DEFINE is added by using the following TACL
command:
Takeover Procedures
AutoSYNC is commonly used with database-replication products to provide complete
business continuity and disaster recovery. Those products have various methods to
discontinue the replication process and to bring the database into a consistent state;
this is commonly known as a takeover. This section describes the basic steps to
perform a takeover for AutoSYNC processing.
Planned Takeover
The primary operation for a planned takeover is to terminate the ongoing scheduled
synchronization from the current primary system to the new primary system.
First, examine the scheduled synchronization file sets using the STATUS SYNC,
DETAIL and INFO SYNCFILESET, LOG commands. If any errors have been reported,
resolve them before attempting the takeover.
Then, issue SUSPEND SYNCUSER and SUSPEND SYNCFILESET commands to
prevent additional synchronization before you switch processing to the new primary
system.
Following the SUSPEND commands, the STATUS SYNC, DETAIL command should
report that there are no scheduled ASYSYNC processes. Note that SUSPEND will
terminate a scheduled synchronization at the end of the current file being
synchronized, so there may still be synchronization activity for a short period.
For safety, the user should also implement the guidelines for unplanned takeovers,
below.
Unplanned Takeover
In this case, the original primary system has ceased functioning and is no longer
synchronizing files to the new primary system. The destination ASYSYNC processes
perform the necessary recovery operations and terminate themselves. There are no
special operations required to bring the AutoSYNC-replicated files into a consistent
state.
However, the user must prepare for the recovery of the original primary system. When
the old primary system is restarted and if the AutoSYNC startup procedures are
ADD DEFINE =_AUTOSYNC_SYSDB,CLASS CATALOG,SUBVOL $vol.mysysdb