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From Aaron Morton <>
Subject Re: Reducing the number of vnodes
Date Tue, 06 Aug 2013 07:57:49 GMT
Repair runs in two phases, first it works out the differences then it streams the data. The
length of the first depends on the size of the data and the second on the level of inconsistency.

To track the first use nodetool compaction stats or look in the logs for the messages about
requesting or receiving Merkle Tree's. 

To track the second use nodetool netstats or look in the logs for messages about streaming
X number of ranges.

Hope that helps. 
Aaron Morton
Cassandra Consultant
New Zealand


On 6/08/2013, at 1:41 AM, Christopher Wirt <> wrote:

> 1.2.4. Really hesitant to upgrade versions due to the inevitable issues it will cause.
> Guess I could upgrade a single node and let that run for a while before upgrading all
> From: Haithem Jarraya [] 
> Sent: 05 August 2013 13:04
> To:
> Subject: Re: Reducing the number of vnodes
> Chris,
> Which C* version are you running? 
> You might want to do an upgrade to the latest version before reducing the vnode counts,
a lot of fixes and improvement went in lately, it might help you getting your repair faster.
> H
> On 5 Aug 2013, at 12:30, Christopher Wirt <> wrote:
> Hi,
> I’m thinking about reducing the number of vnodes per server.
> We have 3 DC setup – one with 9 nodes, two with 3 nodes each.
> Each node has 256 vnodes. We’ve found that repair operations are beginning to take
too long.
> Is reducing the number of vnodes to 64/32 likely to help our situation?
> What options do I have for achieving this in a live cluster?
> Thanks,
> Chris

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