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From Akhil Mehra <akhilme...@gmail.com>
Subject Re: Cleaning up related issue
Date Mon, 19 Jun 2017 09:14:30 GMT
The nodetool cleanup docs explain this increase in disk space usage.

"Running the nodetool cleanupcommand causes a temporary increase in disk space usage proportional
to the size of your largest SSTable. Disk I/O occurs when running this command."

http://docs.datastax.com/en/cassandra/2.1/cassandra/tools/toolsCleanup.html <http://docs.datastax.com/en/cassandra/2.1/cassandra/tools/toolsCleanup.html>

Cheers,
Akhil


> On 19/06/2017, at 7:47 PM, wxn002@zjqunshuo.com wrote:
> 
> Akhil, I agree with you that the node still has unwanted data, but why it has more data
than before cleaning up?
> 
> More background:
> Before cleaning up, the node has 790GB data. After cleaning up, I assume it should has
less data. But in fact it has 1000GB data which is larger than I expected.
> Cassandra daemon crashed and left the files with the name with "tmp-" prefix in the data
directory which indicate the cleaning up task was not complete.
> 
> Cheers,
> -Simon
>  
> From: Akhil Mehra <mailto:akhilmehra@gmail.com>
> Date: 2017-06-19 15:17
> To: wxn002@zjqunshuo.com <mailto:wxn002@zjqunshuo.com>
> CC: user <mailto:user@cassandra.apache.org>
> Subject: Re: Cleaning up related issue
> When you add a new node into the cluster data is streamed for all the old nodes into
the new node added. The new node is now responsible for data previously stored in the old
node.
>  
> The clean up process removes unwanted data after adding a new node to the cluster.
>  
> In your case clean up failed on this node.
>  
> I think this node still has unwanted data that has not been cleaned up.
>  
> Cheers,
> Akhil
>  
>  
>  
>  
> > On 19/06/2017, at 7:00 PM, wxn002@zjqunshuo.com wrote:
> >
> > Thanks for the quick response. It's the existing node where the cleanup failed.
It has a larger volume than other nodes.
> >  
> > From: Akhil Mehra
> > Date: 2017-06-19 14:56
> > To: wxn002
> > CC: user
> > Subject: Re: Cleaning up related issue
> > Is the node with the large volume a new node or an existing node. If it is an existing
node is this the one where the node tool cleanup failed.
> >
> > Cheers,
> > Akhil
> >
> >> On 19/06/2017, at 6:40 PM, wxn002@zjqunshuo.com wrote:
> >>
> >> Hi,
> >> After adding a new node, I started cleaning up task to remove the old data on
the other 4 nodes. All went well except one node. The cleanup takes hours and the Cassandra
daemon crashed in the third node. I checked the node and found the crash was because of OOM.
The Cassandra data volume has zero space left. I removed the temporary files which I believe
created during the cleaning up process and started Cassanndra.
> >>
> >> The node joined the cluster successfully, but one thing I found. From the "nodetool
status" output, the node takes much data than other nodes. Nomally the load should be 700GB.
But actually it's 1000GB. Why it is larger? Please see the output below.
> >>
> >> UN  10.253.44.149   705.98 GB  256          40.4%             9180b7c9-fa0b-4bbe-bf62-64a599c01e58
 rack1
> >> UN  10.253.106.218  691.07 GB  256          39.9%             e24d13e2-96cb-4e8c-9d94-22498ad67c85
 rack1
> >> UN  10.253.42.113   623.73 GB  256          39.3%             385ad28c-0f3f-415f-9e0a-7fe8bef97e17
 rack1
> >> UN  10.253.41.165   779.38 GB  256          40.1%             46f37f06-9c45-492d-bd25-6fef7f926e38
 rack1
> >> UN  10.253.106.210  1022.7 GB  256          40.3%             a31b6088-0cb2-40b4-ac22-aec718dbd035
 rack1
> >>
> >> Cheers,
> >> -Simon


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