[
https://issues.apache.org/jira/browse/HDFS-528?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12742401#action_12742401
]
Todd Lipcon commented on HDFS-528:
----------------------------------
Steve: see Dhruba's comment above. In the case of an entirely empty DFS it
makes sense that the NN should stay in safe mode until at least one DN shows
up. This will help with some newbie errors where the DFS appears to be running
but in fact nothing works right because there are no DNs. It also helps with
the issue Dhruba mentioned involving unneeded replication during startup, and
is more principled than just picking a large number for dfs.safemode.extension.
I've got the bug I mentioned last night fixed and will upload a new patch after
I do a bit of "burn in" in our sandbox.
> Add ability for safemode to wait for a minimum number of live datanodes
> -----------------------------------------------------------------------
>
> Key: HDFS-528
> URL: https://issues.apache.org/jira/browse/HDFS-528
> Project: Hadoop HDFS
> Issue Type: New Feature
> Components: scripts
> Affects Versions: 0.21.0
> Reporter: Todd Lipcon
> Assignee: Todd Lipcon
> Attachments: hdfs-528-v2.txt, hdfs-528-v3.txt, hdfs-528.txt
>
>
> When starting up a fresh cluster programatically, users often want to wait
> until DFS is "writable" before continuing in a script. "dfsadmin -safemode
> wait" doesn't quite work for this on a completely fresh cluster, since when
> there are 0 blocks on the system, 100% of them are accounted for before any
> DNs have reported.
> This JIRA is to add a command which waits until a certain number of DNs have
> reported as alive to the NN.
--
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.
