Manage Replication Acknowledgment
AMPS provides modules for downgrading replication destinations that fall behind and upgrading them again when they catch up.
amps-action-do-downgrade-replication
Downgrades replication connections from synchronous to asynchronous if the age of the last acknowledged message is older than a specified time period.
amps-action-do-upgrade-replication
Upgrades previously-downgraded replication connections from asynchronous to synchronous if the age of the last acknowledged message is more recent than a specified time period.
This action has no effect on replication destinations that are specified as async in the configuration file.
The modules determine when to downgrade and upgrade based on the age of the oldest message that a destination has not yet acknowledged. When using these modules, it is important that the thresholds for the modules are not set too close together, otherwise; AMPS may repeatedly upgrade and downgrade the connection when the destination is consistently acknowledging messages at a rate close to the threshold values. To avoid this, 60East recommends that the Age set for the upgrade module is 1/2 of the age used for the downgrade module.
The amps-action-do-downgrade-replication module accepts the following options:
Age
(required)
Specifies the maximum message age at which AMPS downgrades a replication destination to async.
When this action runs, AMPS downgrades any destination for which the oldest unacknowledged message is older than the specified Age.
For example, when the Age is 5m, AMPS will downgrade any destination where a message older than 5 minutes has not been acknowledged.
There is no default for this parameter.
GracePeriod
The approximate time to wait after start up before beginning to check whether to downgrade links.
The GracePeriod allows time for other AMPS instances to start up and for connections to be established between AMPS instances.
The amps-action-do-upgrade-replication module only applies to destinations configured as sync that have been previously downgraded. The module accepts the following options:
Age
(required)
Specifies the maximum message age at which a previously-downgraded destination will be upgraded to sync mode.
When this action runs, AMPS upgrades any destination that has been previously downgraded where the oldest unacknowledged message is more recent than the time value specified in the Age parameter.
For example, if a destination has been downgraded to async mode and the Age is 2m, AMPS will upgrade the destination when the oldest unacknowledged message to that destination is less than 2 minutes old.
There is no default for this parameter.
GracePeriod
The approximate time to wait after start up before beginning to check whether to upgrade links.
The GracePeriod allows time for other AMPS instances to start up, and for connections to be established between AMPS instances.
These modules do not add any variables to the AMPS context.
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