SNAX/APC Configuration and Management Manual

Objects for SNAX/APC
SNAX/APC Configuration and Management Manual—138787
7-12
LU States
access method, the object returns to the STARTING state until the open is
successfully retried at which time the object enters the STARTED state.
In either of these cases, the STARTING state is an error state. If any object sits in
the STARTING state for very long, it is in a error condition.
5. The LU object enters the STOPPED state from the STARTING state or the
STARTED state upon receipt of the ABORT or STOP command.
6. The LU object ceases to exist when it receives a DELETE command while in the
STOPPED state.
Figure 7-3
illustrates the effects of different requests and commands on the LU object.
Automatic Error Recovery
When an LU receives a file system error from its underlying SNAX access method (such
as SNAX/APN or SNAX/XF), the LU issues a CLOSE request to the access method and
performs all of the necessary clean up activities. All of the sessions are terminated
because of the interruption by the file system error. A Session Outage Notification
(SON) is sent to the upper layers of the LU 6.2 protocol. All active conversations are
terminated with a resource failure indication.
Once the cleanup is done, the LU retries the OPEN request to its underlying SNAX
access method. If the underlying SNAX access method recovered from the previous
fault and accepts the OPEN request, the LU stays in the STARTED state and remains
available for use. If the LU receives a second file system error for this OPEN request,
SNAX/APC places the LU and all of its subordinates in the STARTING state, starts a
Figure 7-3. The LU States
103CDT .CDD
Nonexisting
STOPPED
ADD
Command
DELETE
Command
ABORT
or STOP
Command
STARTING
TP-READY triggers
the open to the access
method and the open
is successful.
A file system error is received from the
underlying access method.
ABORT or STOP Command
STARTED
START Command
START/TP-READY/RETRY
(LU open SNAX file failed)