Partition distribution between nodes

Manu Mäki - Compare Group m.maki at comparegroup.eu
Tue Jun 3 02:51:56 EDT 2014


Hi Luke,

Do you have any idea why creating the cluster from scratch creates "more balanced" cluster? Is this because of the actual partition sizes not being of equal size?


Manu

From: Luke Bakken <lbakken at basho.com<mailto:lbakken at basho.com>>
Date: Monday 2 June 2014 19:34
To: Manu Maki <m.maki at comparegroup.eu<mailto:m.maki at comparegroup.eu>>
Cc: "riak-users at lists.basho.com<mailto:riak-users at lists.basho.com>" <riak-users at lists.basho.com<mailto:riak-users at lists.basho.com>>
Subject: Re: Partition distribution between nodes

Hi Manu,

I see similar vnode distribution in my local dev cluster. This is due to 64 not being evenly divisible by 5.

4 nodes:

$ dev1/bin/riak-admin member-status
================================= Membership ==================================
Status     Ring    Pending    Node
-------------------------------------------------------------------------------
valid      25.0%      --      'dev1 at 127.0.0.1<mailto:dev1 at 127.0.0.1>'
valid      25.0%      --      'dev2 at 127.0.0.1<mailto:dev2 at 127.0.0.1>'
valid      25.0%      --      'dev3 at 127.0.0.1<mailto:dev3 at 127.0.0.1>'
valid      25.0%      --      'dev4 at 127.0.0.1<mailto:dev4 at 127.0.0.1>'
-------------------------------------------------------------------------------

5th node added:

$ dev1/bin/riak-admin member-status
================================= Membership ==================================
Status     Ring    Pending    Node
-------------------------------------------------------------------------------
valid      18.8%      --      'dev1 at 127.0.0.1<mailto:dev1 at 127.0.0.1>'
valid      18.8%      --      'dev2 at 127.0.0.1<mailto:dev2 at 127.0.0.1>'
valid      18.8%      --      'dev3 at 127.0.0.1<mailto:dev3 at 127.0.0.1>'
valid      25.0%      --      'dev4 at 127.0.0.1<mailto:dev4 at 127.0.0.1>'
valid      18.8%      --      'dev5 at 127.0.0.1<mailto:dev5 at 127.0.0.1>'
-------------------------------------------------------------------------------

Cluster from scratch with 5 nodes:

$ dev1/bin/riak-admin member-status
================================= Membership ==================================
Status     Ring    Pending    Node
-------------------------------------------------------------------------------
valid      20.3%      --      'dev1 at 127.0.0.1<mailto:dev1 at 127.0.0.1>'
valid      20.3%      --      'dev2 at 127.0.0.1<mailto:dev2 at 127.0.0.1>'
valid      20.3%      --      'dev3 at 127.0.0.1<mailto:dev3 at 127.0.0.1>'
valid      20.3%      --      'dev4 at 127.0.0.1<mailto:dev4 at 127.0.0.1>'
valid      18.8%      --      'dev5 at 127.0.0.1<mailto:dev5 at 127.0.0.1>'
-------------------------------------------------------------------------------

--
Luke Bakken
CSE
lbakken at basho.com<mailto:lbakken at basho.com>


On Mon, Jun 2, 2014 at 6:52 AM, Manu Mäki - Compare Group <m.maki at comparegroup.eu<mailto:m.maki at comparegroup.eu>> wrote:
Hi all,

In the beginning we were running four nodes with n-value of 2. The partitions were distributed 25% for each node. Now when we added fifth node (still having n-value of 2), the partitions are distributed in following way: 25%, 19%, 19%, 19% and 19%. The ring size in use is 64. Is this normal behavior? The cluster seems to be working correctly. However I was expecting each node to have 20% of the partitions.


Best regards,
Manu Mäki

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