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From "Josh Elser (JIRA)" <>
Subject [jira] [Commented] (ACCUMULO-1454) Need good way to perform a rolling restart of all tablet servers
Date Tue, 12 Aug 2014 18:47:13 GMT


Josh Elser commented on ACCUMULO-1454:

bq. start a lot of new tserver instances

This might be more difficult than it sounds. {{}} is fairly easy to manage,
but {{}} is pretty aggressive about just {{kill}}'ing the process on a host.
I think we might have to expand on the shell scripts to really give an admin what they want.

bq. migrate tablets <tserver instance src> <tserver instance dest>

Would you consider this a FATE op that the master coordinates, or would you just add something
directly to the TServer and let the client handle the coordination? Would that just bash ZooKeeper
trying to migrate tablets off of ~200 tservers? (e.g. 200 tservers * 200 tablets)?

> Need good way to perform a rolling restart of all tablet servers
> ----------------------------------------------------------------
>                 Key: ACCUMULO-1454
>                 URL:
>             Project: Accumulo
>          Issue Type: Improvement
>          Components: tserver
>    Affects Versions: 1.4.3, 1.5.0
>            Reporter: Mike Drob
> When needing to change a tserver parameter (e.g. java heap space) across the entire cluster,
there is not a graceful way to perform a rolling restart.
> The naive approach of just killing tservers one at a time causes a lot of churn on the
cluster as tablets move around and zookeeper tries to maintain current state.
> Potential solutions might be via a fancy fate operation, with coordination by the master.
Ideally, the master would know which servers are 'safe' to restart and could minimize overall
impact during the operation.

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