THIS IS A TEST INSTANCE. ALL YOUR CHANGES WILL BE LOST!!!!
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| Upgrade Type | Pros | Cons |
|---|---|---|
| Rolling Upgrade (RU) | Minimal cluster downtime - services available throughout upgrade process | Takes time (sometimes days depending on cluster size) due to incremental upgrade approach |
| Express Upgrade (EU) | Cluster unavailable - services are stopped during upgrade process | Much faster - clusters can be upgraded in a couple of hours |
Each component which has to be upgraded by Ambari should specify the versionAdvertised flag in the metainfo.xml.
This will tell Ambari to use the component's version and perform upgrade. Not specifying this flag will result in Ambari not upgrading the component.
Example: HDFS NameNode (versionAdvertised=true), AMS Metrics Collector (versionAdvertised=false).
Rolling Upgrades
In Rolling Upgrade each service is upgraded with minimal downtime in mind. The general approach is to quickly upgrade the master components, followed by upgrading of workers in batches.
The service will not be available when masters are restarting. However when master components are in High Availability (HA), the service continues to be available through restart of each master.
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