67 lines
2.4 KiB
ReStructuredText
67 lines
2.4 KiB
ReStructuredText
Admin Schedulers
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================
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The Admin API has several schedulers to maintain the health of the Libra
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system. This section of the document goes into detail about each one.
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Each Admin API server takes it in-turn to run these tasks. Which server is
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next is determined by the :option:`--number_of_servers` and
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:option:`--server_id` options.
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Stats Scheduler
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---------------
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This scheduler is actually a monitoring scheduler and at a later date will also
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gather statistics for billing purposes. It is executed once a minute.
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It sends a gearman message to active Load Balancer device. There are three
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possible outcomes from the results:
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#. If all is good, no action is taken
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#. If a node connected to a load balancer has failed the node is marked as
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ERROR and the load balancer is marked as DEGRADED
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#. If a device has failed the device will automatically be rebuilt on a new
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device and the associated floating IP will be re-pointed to that device. The
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old device will be marked for deletion
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Delete Scheduler
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----------------
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This scheduler looks out for any devices marked for deletion after use or after
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an error state. It is executed once a minute.
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It sends a gearman message to the Pool Manager to delete any devices that are
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to be deleted and removes them from the database.
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Create Scheduler
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----------------
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This scheduler takes a look at the number of hot spare devices available. It
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is executed once a minute (after the delete scheduler).
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If the number of available hot spare devices falls below the value specified by
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:option:`--node_pool_size` it will request that new devices are built and those
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devices will be added to the database. It records how many are currently being
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built so long build times don't mean multiple Admin APIs are trying to fulfil
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the same quota.
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VIP Scheduler
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-------------
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This scheduler takes a look at the number of hot spare floating IPs available.
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It is executed once a minute.
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If the number of available floating IP address falls below the value specified
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by :option:`vip_pool_size` it will request that new IPs are build and those
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will be added to the database.
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Expunge Scheduler
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-----------------
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This scheduler removes logical Load Balancers marked as DELETED from the
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database. It is executed once a day.
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The DELETED logical Load Balancers remain in the database mainly for billing
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purposes. This clears out any that were deleted after the number of days
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specified by :option:`--expire-days`.
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