bhuvnesh chaudhary created AMBARI-14749:
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Summary: Introduce ADD HAWQ STANDBY wizard to enable high
availability in HAWQ
Key: AMBARI-14749
URL: https://issues.apache.org/jira/browse/AMBARI-14749
Project: Ambari
Issue Type: New Feature
Components: stacks
Reporter: bhuvnesh chaudhary
This patch introduces another high availability wizard which adds HAWQ Standby
component to the HAWQ cluster.
Why it is required?
Apache HAWQ database has the below components.
- Master
- Standby
- Segments
At any point of time, database connections are only accepted by the master and
it is the single point of entry for read and write operations. In the
background, there is a sync-up process which ensures that standby component is
in sync with master, so that in case master goes down, HAWQ standby can be
promoted to perform the role of master and there is minimum downtime.
However, in order to enable High Availability operation for HAWQ, HAWQ standby
must be configured to the cluster and required configuration changes must be
done to ensure that HAWQ Standby is operational and in sync.
After HAWQ Standby is added and if it has been promoted / activated to take the
role of the HAWQ Master, the HAWQ cluster now operates in non-HA mode. The old
HAWQ master is out of the cluster and cannot be transitioned to the role of
Standby. In order to get back to HA state, a standby has to be added to the
cluster.
In this patch, the functionality to add HAWQ Standby Master has been introduced
which performs the following functions:
- Disable / Enable "Add HAWQ Standby" option depending on the state of the
cluster. If HAWQ Standby is configured, this option is not visible. If HAWQ
Standby is not configured and the cluster is not single node, the option is
visible.
- When the action is triggered, "Add HAWQ Standby" wizard comes into role - -
The wizard contains of 4 pages which does a dedicated job
- Page 1: It gives information to the user for the activities which will be
carried out by the wizard
- Page 2: It lets' the user chose the host on which standby should be installed
- Page 3: Informs the user about the configuration changes which will take
place based on the inputs on Page 2
- Page 4: Below list of operations are carried.
1. Stop HAWQ Service
2. Install HAWQ Standby Component
3. Reconfigure HAWQ Service to add required properties
4. Start HAWQ service. During this step, hawq standby is initialized and
started.
- After the wizard completes, HAWQ standby is added to the cluster and now HAWQ
is operational in HA mode.
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