EC2 and node names

Jeff Pollard jeff.pollard at gmail.com
Tue May 3 13:35:28 EDT 2011


Grant,

Thanks for the reply.  I think I understand what you're saying, but it's not
100% clear to me how exactly it applies to my question.  I'll try explaining
my plan another way if that helps.

Imagine we have 4 nodes running in a ring on EC2: riak at 10.5.0.1,
riak at 10.5.0.2, riak at 10.5.0.3, riak at 10.5.0.4.  Then one day node
riak at 10.5.0.3 goes down and is unrecoverable.  Our plan had been:

# On a existing node in the cluster
riak-admin remove riak at 10.5.0.3
riak-admin ringready
# .. wait for TRUE

# Boot a new EC2 machine configured as riak at 10.5.0.5 (brand new IP)
# Then on that new machine...
riak start
riak-admin join riak at 10.5.0.1
riak-admin ringready
# .. wait for TRUE

In that scenario, I imagine the issue is that removing and adding a new node
under a new node name is putting extra strain on the cluster to shift data
around?  Simply replacing a new node under the same hostname (even though it
has a different IP) would mean less work for the cluster?  And how much
extra work are

Thanks!

On Tue, May 3, 2011 at 6:24 AM, Grant Schofield <grant at basho.com> wrote:

>
> On May 2, 2011, at 7:58 PM, Jeff Pollard wrote:
>
> I was reviewing the Riak Operations webinar<http://blog.basho.com/2011/04/15/follow-up-to-riak-operations-webinar/>,
> and it was mentioned that the preferred vm.args -name for EC2 environments
> should be "riak at hostname" because you don't have to "rename data or do
> anything weird" like you would if your nodes were named "riak at ip.address"
> (approximately 40:05 in the video).
>
> I was looking for some elaboration on this tip, namely:
>
>    1. What is meant by "rename data or do anything weird"
>
> When you bring a cluster together using data copied from a different set of
> nodes you need to re-ip the first node you plan to start but you also have
> to change the ring manually on that node so when the subsequent nodes join
> everything works properly.
>
>
>    1. Is "hostname" in riak at hostname a public DNS host that you configure
>    in your DNS to map to the EC2 public hostname (ec2-50-18-...)?
>
> You can use DNS (public or private) or host file entries that reference the
> private IP of the node if you choose to use hostname.
>
>
>    1. Does anyone have any best practices around vm.args -name in EC2
>    environments?
>
> We haven't outlined any best practices ourselves, but I tend to believe
> using a hostname that you can change the IP for via DNS or a hosts file is a
> more flexible way of approaching the problem.
>
> Grant
>
>
> Thanks!
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>
>
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