[jira] [Commented] (HBASE-27700) rolling-restart.sh stop all masters at the same time

["Jack Yang (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HBASE-27700?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17698752#comment-17698752 ] 

Jack Yang commented on HBASE-27700:
-----------------------------------

Seeing the discussion of here: https://lists.apache.org/thread/scz6tqy97d9rg3lzdv85g3qlbdvyqnt4

> rolling-restart.sh stop all masters at the same time
> ----------------------------------------------------
>
>                 Key: HBASE-27700
>                 URL: https://issues.apache.org/jira/browse/HBASE-27700
>             Project: HBase
>          Issue Type: Improvement
>            Reporter: Jack Yang
>            Priority: Minor
>
> The rolling-restart.sh in $HBASE_HOME/bin would stop all master service (including the backup ones) at the same time, and then restart them at the same time:
> {code:java}
> # The content of rolling-restart.sh
> ...
> # stop all masters before re-start to avoid races for master znode
> "$bin"/hbase-daemon.sh --config "${HBASE_CONF_DIR}" stop master
> "$bin"/hbase-daemons.sh --config "${HBASE_CONF_DIR}" \
> --hosts "${HBASE_BACKUP_MASTERS}" stop master-backup
> # make sure the master znode has been deleted before continuing
> zmaster=`$bin/hbase org.apache.hadoop.hbase.util.HBaseConfTool
> zookeeper.znode.master`
> ...
> # all masters are down, now restart
> "$bin"/hbase-daemon.sh --config "${HBASE_CONF_DIR}"
> ${START_CMD_DIST_MODE} master
> "$bin"/hbase-daemons.sh --config "${HBASE_CONF_DIR}" \
> --hosts "${HBASE_BACKUP_MASTERS}" ${START_CMD_DIST_MODE} master-backup {code}
> In this way the HMaster service would be unavailable during this period. We can restart them in a more graceful way, like this:
>  * Stop the backup masters, and then restart them one by one
>  * Stop the active master, then one of the backup master would become active
>  * Start the original active master, now it's the backup one
> Will upload patch soon.



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