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#Failover

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High Availability Failover is the ability for client connections to migrate from one server to another in event of server failure so client applications can continue to operate.

See more on Failover strategies.

We are trying to script a High Availability Shutdown/Start script in case we need to fail over to one of our other servers we can be back up within mins. Is there a way to configure the startup procedure to Automatically Stop/Start the JDBC server when shutting down or starting up cache? is there an auto setting we can change?

Thanks

Scott Roth

The Ohio State University Wexner Medical Center

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I've created a scheduled task that dumps HL7 messages to flat files. It uses the OutputToLibraryStream() method of EnsLib.HL7.Message. I'd like to be able to run it on a mirror member host whether it's primary or backup.

When run against a database that's mounted read-only, it works fine. However, when I attempt to run it against a mirror backup database, I get the following error:

#5002: Cache error: <PROTECT>%LoadData+7^EnsLib.HL7.Message.1

Tracing that back to the source, I find:

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In System Administration | Configuration | System Configuration | Journal Settings there is a check box for Freeze on error.

From reading the documentation, it sounds like the choice to freeze on error is one of system availability vs system integrity.

Curious to know whether Ensemble users choose to freeze on error or not.

If you have a best practice recommendation based upon your experience or knowledge, that would be helpful information too.

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Question
· Nov 9, 2017
Detecting and managing failover

I have Ensemble/Healthshare running in a production environment which is setup with a mirror failover and an arbiter sitting between them.

In the event of a failover we have a number of connections that need stopping/monitoring and starting in a certain order.

Is there a programmatic way we can detect the failover and stop certain services and operations immediately and then start them up again in the required order, checking their connection state before starting the next connection.

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Hi:
The task Mirror Monitor Launch Task recently failed and is placed in Suspend leave. Although it says USER it is not known as a task for us.

The code runs is HSSYS which is not our main system or namespace for production items.

The task name is HS.Util.Mirror.Task runs

If $system.Mirror.IsMember() Do ##class(HS.Util.MirrorMonitorAgent).StartAgent() and just says the description

/// This is the task definition that Launches the mirror monitor on any mirrored instance

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