HP Integrity NonStop J-Series - Manual (Page 70)

Scheduled Synchronization
HP AutoSYNC User’s Guide—522580-018
4-10
ASYSYNC process
ASYSYNC process
The ASYSYNC process on the destination is started by the ASYSYNCP process on
the source and thus automatically has the appropriate process-access ID. The
ASYSYNC process receives a single file set description and a list of all files in the
source file set.
The ASYSYNC process then finds all files in the destination file set. If the PURGE or
SUBVOLPURGE option is specified, extra files in the destination file set are purged.
The names of files that are missing from the destination, as well as files that meet
other criteria for synchronization, are returned to the ASYSYNCP process. After the
exchange of file information, the data stream of file data is received and used to create
or replace the destination copies of the source files.
When a replacement file is received, ASYSYNC renames the existing file to save it and
proceeds to write the new file; it also records the information to an index file on the
same disk. If the new file is received successfully, the saved file is purged. If any error
occurs, ASYSYNC purges the new file and renames the saved file back to its original
file name.
In the event that an ASYSYNC process (or its CPU) fails before it can effect recovery,
any subsequent synchronization to the same disk volume will access the index file and
perform the recovery.
Variant for Synchronization over TCP/IP
If the file sets received by ASYSYNCP from the monitor process specify a TCP/IP
address, the synchronization occurs over a TCP/IP link rather than EXPAND.
In this case, the source ASYSYNCP does not directly start the destination
synchronization process ASYSYNC. Instead, ASYSYNCP connects to the monitor
process on the destination system using a user-configured port. The destination
monitor then starts an ASYSYNCP process. The destination ASYSYNCP performs a
log down from the access ID of the destination AutoSYNC authorizer to the access ID
of the user that requests the synchronization. Due to the requirement to perform a log
down on the destination system, both the source and destination synchronization
processes are ASYSYNCP objects.
Then the communication between source and destination ASYSYNCP is established
and the synchronizations proceed as described above in paragraphs
ASYSYNCP
process and ASYSYNC process .
See Synchronization Over TCP/IP on page 7-1 for further details.