Sierra Video Yosemite - Manual (Page 74)

SIERRA VIDEO
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Processor Synchronization
The “usual state of affairs” for redundant processors is that both processors always power up at the same
time, and continue to operate until power down. In that situation, the standby processor always is up-to-
date with regard to any router configuration information that the master processor has received
(crosspoints, salvos, panel’s settings, input/output/level names, etc). If the standby processor must relieve
the master, it has all the information it needs to do so.
This “usual state of affairs” may not be the case, however. If one processor is removed from the routing
switcher, it will no longer have the same router configuration information as the processor that is still
controlling the systems as master. When this happens, it is important that the two processors
“resynchronize” their configuration information as soon as the second processor is put back into the
chassis. Resynchronization involves the transfer of a considerable amount of information from the current
master processor to the standby processor. If the standby processor becomes master before the
synchronization process is finished, the router may be running with outdated configuration information.
During the synchronization process, LEDb will flash. When it stops flashing, synchronization is complete.
Completion may take approximately ten minutes after powering on the router.
The synchronization process is always done at power-up, even if the two processors are actually already
in sync because they have always been powered on together. The processors have no way of knowing
that they are in sync, without actually performing the synchronization process.
When it is necessary to remove a processor from the frame, the master processor should not be removed
while the synchronization process is occurring, i.e. while LEDb is flashing. If it is removed, the standby
processor will take over with possibly out-of-date configuration information. If saving up-to-date
information is not an issue, the master processor can be removed at any time.
The standby processor can be removed at any time, even during synchronization, with no negative
impact on operation. When it is reinserted, the synchronization process will be restarted.
When the routing switcher is powered on with two processor that were not synced to one another the last
time they were running, the processor with the most up-to-date configuration should have switch S1-1
turned ON. This processor should be the one in the left-upper most corner. If the processor with the older
configuration data was the one with S1-1 turned ON, it would again become the master processor and
would send its older data to the standby processor, wiping out it newer data.
Note: if it is necessary to remove a processor from the routing switcher, the master
processor should not be removed while the synchronization process is happening, i.e.
while LEDb is flashing
Synchronizing Host and Terminal Protocols on Both Processors
Ports 1 and 2 can run either Host or Terminal protocol. If both processors are powered on at the same
time, they should both stay in sync with one another, and the ports on the two processors should be
running the same protocols. If the standby processor is inserted after the master has been running for a
while, the synchronization process causes the standby processor to switch to running the same protocol
as the master processor. However, the standby processor may not be in sync with the master processor
within that protocol.
For example, suppose the master processor is running Host protocol on Port 1, and a partial command
has been sent to the port. Then, the standby processor starts up, and the rest of the command is sent to
the Port 1. The standby processor never sees the first part of the command and will ignore the entire
command. This situation is unlikely to cause problems because commands are usually sent quickly.
When the synchronization process is complete, both processors have the data in sync, and both are
processing complete host commands.