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From "Keith Turner (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (ACCUMULO-1832) Create utility for rewriting uris
Date Wed, 29 Jan 2014 21:02:12 GMT

    [ https://issues.apache.org/jira/browse/ACCUMULO-1832?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13885810#comment-13885810
] 

Keith Turner commented on ACCUMULO-1832:
----------------------------------------

Looking at the utility that was created, I think it makes the following assumptions :

 * All volumes in use are no longer accessible
 * No tablets are currently loaded

I think if any of these assumptions are not true, then the utility will not work so well.
  An example situation is new a DNS addr for the namenode is planned. For a short period of
time the new and old namenode DNS addrs work.  An admin wants to use this utility to replace
the old DNS addrress.  The current utility would make changes to loaded tablets metadata,
which would make Accumulo very unhappy.  I am thinking removing the script and doing the following
to solve this problem.

 * Support storing a list of URI rename in zookeeper or in accumulo-site.xml (maybe make it
a tserver or general config so it could be in either)
 * When each tablet loads it checks its paths against this list of renames and if changes
are needed it does them.

Also I think admins will need a utility to list all unique URI prefixes in use by Accumulo.
 This utility should start w/ zookeeper, then root table, then metadata table listing unique
URIs used by each one.  This utility would allow admins to find URI that need to replaced
that they were not aware of.  Also it will allow them to know when the rename is done and
the config can be removed.

I am going to experiment w/ this approach.
 

  

> Create utility for rewriting uris
> ---------------------------------
>
>                 Key: ACCUMULO-1832
>                 URL: https://issues.apache.org/jira/browse/ACCUMULO-1832
>             Project: Accumulo
>          Issue Type: Sub-task
>          Components: master, tserver
>            Reporter: Keith Turner
>            Assignee: Eric Newton
>            Priority: Blocker
>             Fix For: 1.6.0
>
>
> When a users namenode dies and they restore it on another node Accumulo will not work
since it stores fully qualified uris internally.  Need to a provide a utility to rewrite these
URIs.
> The utility  could rewrite paths in zookeeper, bring root table online and rewrite paths,
bring metadata table online and rewrite, and then allow user tablets to come online.



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