Redundant Aspect Servers for AC400 Connect
Good Morning , we have a customer , it has installed 2 Aspect Servers primary and redundant , two redundant connectivity servers 1 AC450 , 1 AC410. Primary aspect server has showed a hardware problem because of that it is shutdown .
Customer had an IO Problem in the AC450 controller and he had to reassign a tag object to another channel they had to upload the modification to the 800xA as you know using upload aspect.
The question is , Is there any problem about that it may be in the future they could need to do another upload procedure ,
it means secondary aspect server has different information compared against primary aspect server
When we turn primary aspect server on , Primary Aspect Server would synchronize the information with Secondary Aspect Server and it would not be any problem
It is an old version of 800xA ( 4.1)
Regards
Ricardo
Customer had an IO Problem in the AC450 controller and he had to reassign a tag object to another channel they had to upload the modification to the 800xA as you know using upload aspect.
The question is , Is there any problem about that it may be in the future they could need to do another upload procedure ,
it means secondary aspect server has different information compared against primary aspect server
When we turn primary aspect server on , Primary Aspect Server would synchronize the information with Secondary Aspect Server and it would not be any problem
It is an old version of 800xA ( 4.1)
Regards
Ricardo
Asked 3 months ago
Voted best answer
3
Your concern is justified.
The Aspect Directory is a transactional database with an ever increasing sequence number. In the above situation, the sequence number of AS2 will continue to increase while AS1 is halted.
When AS1 is started, it should detect this "own sequence is lower than peer's" situation and synchronize. All is fine here...
However, if AS1 should be started while AS2 is offline/not reachable (or was modified while not connected to AS2 before being shutdown) it will enter service state and contain "old" data.
Then once AS2 is started or connected, it will not force AS1 to update, instead one of them may enter "Error" state and set a status code you can translate with the afwerrorlookup.exe tool to "E_AFW_AD_INCOMPATIBLE_VERSION".
Don't get startled if you end up here; just perform Stop Server on AS1, rename the \OperateITData\AspDir folder (and restart AS2 if it went into this error) then start AS1 again. This will ensure AS1's Aspect Directory is cold started towards AS2.
If this had been 5.1 or onwards, there is even one more caveat since the introduction of "1oo2 Automatic Aspect Directory Recovery" where the first listed Aspect Directory service provider (in the Service Group configuration) will automatically overwrite the second. This may wipe the contents of AS2 (which you in this special situation want to keep). Again, renaming the AspDir folder before restarting any "old" Aspect Server is your savior.
And never forget Murphy's First Law of Computers - "Backup often, backup early".
The Aspect Directory is a transactional database with an ever increasing sequence number. In the above situation, the sequence number of AS2 will continue to increase while AS1 is halted.
When AS1 is started, it should detect this "own sequence is lower than peer's" situation and synchronize. All is fine here...
However, if AS1 should be started while AS2 is offline/not reachable (or was modified while not connected to AS2 before being shutdown) it will enter service state and contain "old" data.
Then once AS2 is started or connected, it will not force AS1 to update, instead one of them may enter "Error" state and set a status code you can translate with the afwerrorlookup.exe tool to "E_AFW_AD_INCOMPATIBLE_VERSION".
Don't get startled if you end up here; just perform Stop Server on AS1, rename the \OperateITData\AspDir folder (and restart AS2 if it went into this error) then start AS1 again. This will ensure AS1's Aspect Directory is cold started towards AS2.
If this had been 5.1 or onwards, there is even one more caveat since the introduction of "1oo2 Automatic Aspect Directory Recovery" where the first listed Aspect Directory service provider (in the Service Group configuration) will automatically overwrite the second. This may wipe the contents of AS2 (which you in this special situation want to keep). Again, renaming the AspDir folder before restarting any "old" Aspect Server is your savior.
And never forget Murphy's First Law of Computers - "Backup often, backup early".
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