Allan Yang created HBASE-17718:
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Summary: Difference between RS's servername and its ephemeral node
cause SSH stop working
Key: HBASE-17718
URL: https://issues.apache.org/jira/browse/HBASE-17718
Project: HBase
Issue Type: Bug
Affects Versions: 1.1.8, 1.2.4, 2.0.0
Reporter: Allan Yang
Assignee: Allan Yang
After HBASE-9593, RS put up an ephemeral node in ZK before reporting for duty.
But if the hosts config (/etc/hosts) is different between master and RS, RS's
serverName can be different from the one stored the ephemeral zk node. The
email metioned in HBASE-13753
(http://mail-archives.apache.org/mod_mbox/hbase-user/201505.mbox/%3CCANZDn9ueFEEuZMx=pZdmtLsdGLyZz=rrm1N6EQvLswYc1z-H=g...@mail.gmail.com%3E)
is exactly what happened in our production env.
But what the email didn't point out is that the difference between serverName
in RS and zk node can cause SSH stop to work. as we can see from the code in
{{RegionServerTracker}}
{code}
@Override
public void nodeDeleted(String path) {
if (path.startsWith(watcher.rsZNode)) {
String serverName = ZKUtil.getNodeName(path);
LOG.info("RegionServer ephemeral node deleted, processing expiration [" +
serverName + "]");
ServerName sn = ServerName.parseServerName(serverName);
if (!serverManager.isServerOnline(sn)) {
LOG.warn(serverName.toString() + " is not online or isn't known to the
master."+
"The latter could be caused by a DNS misconfiguration.");
return;
}
remove(sn);
this.serverManager.expireServer(sn);
}
}
{code}
The server will not be processed by SSH/ServerCrashProcedure. The regions on
this server will not been assigned again until master restart or failover.
I know HBASE-9593 was to fix the issue if RS report to duty and crashed before
it can put up a zk node. It is a very rare case. But The issue I metioned can
happened more often(due to DNS, config, etc.) and have more severe consequence.
So here I offer some solutions to discuss:
1. Revert HBASE-9593 from all branches, Andrew Purtell has reverted it in
branch-0.98
2. Abort RS if master return a different name, otherwise SSH can't work properly
3. Master receive whatever servername reported by RS and don't change it.
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