DSM/Tape Catalog Management Programming Manual

Communicating With MEDIASRV
DSM/Tape Catalog Management Programming Manual—520481-003
2-8
Opening a MEDIASRV Process
FUP CREATE filename,TYPE E,REC 132, EXT (pri,sec)
If you inhibit logging (by omitting the LOG parameter or its filename argument),
emergency output—output that precedes the abnormal termination of the
process—is sent to the home terminal.
If the specified logging file cannot be accessed, the process does not start.
Opening a MEDIASRV Process
To send SPI commands to a MEDIASRV process, the process is opened using the
#ZSPI qualifier; in other words, the MEDIASRV process name is specified as
$process-name.#ZSPI. For example, if the MEDIASRV process name is $ZMED,
your application would open it as $ZMED.#ZSPI. The #ZSPI qualifier indicates to the
MEDIASRV process that subsequent messages from this process follow the SPI
protocol.
The only open parameter that might be required is sync-depth, which is specified
when the MEDIASRV process is fault tolerant. If sync-depth is specified with a value
greater than 0 and a MEDIASRV process fails while the MEDIASRV process is
executing a command, the command is automatically processed again. When this
occurs, possibly part or all of the command has executed—particularly for a command
that is directed at more than one object. Therefore, sending the command again can
produce an error. For example, if the command changed one or more object summary
states before being canceled, a subsequent command might produce an error
(perhaps ZCOM-ERR-OBJ-ALRDY-IN-SUMSTATE) because the summary states of
some of the objects changed and are not as expected. HP recommends a sync-
depth value of 1.
If the MEDIASRV process is not fault tolerant and a MEDIASRV process failure affects
your command, the operating-system WRITEREAD procedure that sent the command
returns file-system error 201. Another MEDIASRV process is used to retry the
command. File-system errors are described in the Operator Messages Manual.
MEDIASRV processes accept opens from backup processes, so you can design fault-
tolerant management applications.
For more information, see the description of the FILE_OPEN_ procedure in the
Guardian Procedure Calls Reference Manual and the Guardian User’s Guide.
Note. Do not confuse the open described here with the open described in Starting a
MEDIASRV Process Using the PROCESS_CREATE_ Procedure on page 2-4. This open uses
the SPI interface to exchange messages. The open described earlier was used only to send a
startup message to a newly created MEDIASRV process. Once the startup message is
acknowledged, the MEDIASRV process must be closed, and the process reopened for
management, as described here.