HP Integrity NonStop H-Series - Manual (Page 69)

Scheduled Synchronization
HP AutoSYNC User’s Guide—522580-021
4-9
ASYSYNC process
sets; it will use this user ID for all file access, ensuring that a user does not gain
unauthorized access to data.
The file sets are arranged on a schedule time-list and are processed as they become
ready. File sets in an ASYSYNCP are processed serially.
When a file set is processed, the ASYSYNCP process starts an ASYSYNC process on
the destination system. The ASYSYNCP process then gathers information about all the
files of the source file set and forwards them to the ASYSYNC process.
The ASYSYNC process responds with a list of files (or tables) to be synchronized.
ASYSYNCP fetches the files and forwards the data to ASYSYNC. When all data has
been forwarded, it waits for the ASYSYNC process to complete and return its status
and various file counts. Then, the file set is rescheduled according to the INTERVAL,
START, and STOP specifications.
ASYSYNCP then checks its time list of file sets and processes the next one at the
appropriate time.
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