[jira] [Created] (HBASE-8216) Be able to differentiate Power failures from Rack switch reboot

["Amitanand Aiyer (JIRA)" <ji...@apache.org>]

Amitanand Aiyer created HBASE-8216:
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             Summary: Be able to differentiate Power failures from Rack switch reboot
                 Key: HBASE-8216
                 URL: https://issues.apache.org/jira/browse/HBASE-8216
             Project: HBase
          Issue Type: Bug
            Reporter: Amitanand Aiyer
            Assignee: Amitanand Aiyer
            Priority: Minor
             Fix For: 0.89-fb


The master in 0.89-fb waits for 5-6 mins to check if RS'es become accessible; when it sees a co-related failure such as a rack-switch-reboot.

The rationale behind doing this is that it is not worth assigning and reassigning regions -- causing churn, when the rack switch reboots are expected to heal themselves in 5-6 mins. In earlier deployments, where this feature was not present, we used to find ourselves in a bad situation for 30mins-1hr.

However, co-related failures also happen when there is a power failure for the rack. These cases take much longer to heal; so waiting for 5-6 mins is a wasted effort.

The master should be able to differentiate the two scenario, by checking if *any* of the RS in the rack is able to communicate. Unless all the servers in the rack are unaccessible, we should proceed with reassigning the regions.


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