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From "Paulo Motta (JIRA)" <>
Subject [jira] [Commented] (CASSANDRA-12008) Make decommission operations resumable
Date Fri, 22 Jul 2016 13:29:20 GMT


Paulo Motta commented on CASSANDRA-12008:

Overall your approach looks good. thanks. See comments below:

bq. Node state is changed to LEAVING after decommission starts, and current source code prevents
all states different from NORMAL to restart a decommission operation.

We can change that to allow starting a decommission operation only if state is {{NORMAL}}
or {{LEAVING}}, and in addition to that have an {{isDecommissioning}} flag (similar to {{isRebuilding}}
to prevent starting a deccommision while one is still running. We should unset that flag when
the decommission finishes or fails.

bq. So maybe we should adapt StorageService.streamRanges to use RangeStreamer that already
has all implemented.

I agree we can probably reuse the {{available_ranges}} table to store already transferred
ranges during decommission, so let's start with that then since it's simpler. But we will
probably need to truncate the table in the beginning of deccommision to cleanup previous state
from bootstrap/rebuild. we will also need to update the table description to say that it's
also used by decommission.

bq. 2. and 3. may not be necessary because StreamStateStore.handleStreamEvent always updates
SystemKeyspace.available´╝▓anges using SystemKeyspace.updateAvailable´╝▓anges no matter if
the session transferred or received ranges

The problem is that {{RangeStreamer}} is used to receive ranges, while {{StorageService.streamRanges}}
is used to send ranges, so I think adapting {{RangeStreamer}} to send ranges will be non-trivial.
So it will probably easier to adapt {{StorageService.streamRanges}} to register the {{StreamStateStore}}
as a {{StreamPlan}} listener so it will automatically store already transferred ranges during

> Make decommission operations resumable
> --------------------------------------
>                 Key: CASSANDRA-12008
>                 URL:
>             Project: Cassandra
>          Issue Type: Improvement
>          Components: Streaming and Messaging
>            Reporter: Tom van der Woerdt
>            Assignee: Kaide Mu
>            Priority: Minor
> We're dealing with large data sets (multiple terabytes per node) and sometimes we need
to add or remove nodes. These operations are very dependent on the entire cluster being up,
so while we're joining a new node (which sometimes takes 6 hours or longer) a lot can go wrong
and in a lot of cases something does.
> It would be great if the ability to retry streams was implemented.
> Example to illustrate the problem :
> {code}
> 03:18 PM   ~ $ nodetool decommission
> error: Stream failed
> -- StackTrace --
> org.apache.cassandra.streaming.StreamException: Stream failed
>         at
>         at$
>         at$DirectExecutor.execute(
>         at
>         at
>         at
>         at org.apache.cassandra.streaming.StreamResultFuture.maybeComplete(
>         at org.apache.cassandra.streaming.StreamResultFuture.handleSessionComplete(
>         at org.apache.cassandra.streaming.StreamSession.closeSession(
>         at org.apache.cassandra.streaming.StreamSession.complete(
>         at org.apache.cassandra.streaming.StreamSession.messageReceived(
>         at org.apache.cassandra.streaming.ConnectionHandler$
>         at
> 08:04 PM   ~ $ nodetool decommission
> nodetool: Unsupported operation: Node in LEAVING state; wait for status to become normal
or restart
> See 'nodetool help' or 'nodetool help <command>'.
> {code}
> Streaming failed, probably due to load :
> {code}
> ERROR [STREAM-IN-/<ipaddr>] 2016-06-14 18:05:47,275 - [Stream
#<streamid>] Streaming error occurred
> null
>         at$ ~[na:1.8.0_77]
>         at ~[na:1.8.0_77]
>         at java.nio.channels.Channels$
>         at org.apache.cassandra.streaming.messages.StreamMessage.deserialize(
>         at org.apache.cassandra.streaming.ConnectionHandler$
>         at [na:1.8.0_77]
> {code}
> If implementing retries is not possible, can we have a 'nodetool decommission resume'?

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