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From Alain RODRIGUEZ <arodr...@gmail.com>
Subject Re: Ec2Snitch to Ec2MultiRegionSnitch
Date Wed, 24 Apr 2013 06:48:26 GMT
"If you are only using one Available Zone per region then you have only one
rack per DC and the NetworkTopologyStrategy will do the right thing."

So you mean this part doesn't need more testing ? This will work for sure ?
Did you already did it yourself ?

"Because you are going to replicate your data 3 times in each DC so that
each DC can operate with a LOCAL_QUOURM"
Yet I don't get it. Tell me where I am wrong. LOCAL_QUORUM need to
read/write 2 nodes (since RF = 3) per region. So if I use 6 eu-west and 3
us-east, C* will be able to reach the LOCAL_QUORUM everywhere, won't it ?
So why should I use 6 + 6 servers ?

"nodetool rebuild is designed to handle pulling data from another dc, so
you can use it when the local DC does not contain data. i.e. you do not
want a node in the new DC bootstrapping from other nodes in the new DC,
they have no data"
Good to know, thanks about it, as about all your pointers to the doc.

"Cause it's easier to understand than interleaving the nodes and works with
2+ DC's."
Good point.

If your are interested, I'll let you know how all the things go when we'll
add the second DC.


2013/4/24 aaron morton <aaron@thelastpickle.com>

> > You are advising me to test it, what would be a good way of testing it
> (I can use AWS EC2 instances if needed) ?
> If you are only using one Available Zone per region then you have only one
> rack per DC and the NetworkTopologyStrategy will do the right thing.
>
> > Why ? I mean we have maybe only 5% of our customers on the us-east zone,
> what in C* require to have the same number of node on each DC ?
> Because you are going to replicate your data 3 times in each DC so that
> each DC can operate with a LOCAL_QUOURM.
>
> > What is better on adding nodes with no data and then rebuild them
> compared to using the auto_bootstrap ?
>
> nodetool rebuild is designed to handle pulling data from another dc, so
> you can use it when the local DC does not contain data. i.e. you do not
> want a node in the new DC bootstrapping from other nodes in the new DC,
> they have no data.
>
> > Any doc on this ? I am not aware of all the possibilities. Why is this
> the best method according to you ?
>
> http://wiki.apache.org/cassandra/Operations?highlight=%28token%29#Token_selection
> http://www.datastax.com/docs/1.2/initialize/token_generation
>
> Cause it's easier to understand than interleaving the nodes and works with
> 2+ DC's.
>
> > What is the point of this ?
> http://wiki.apache.org/cassandra/FAQ#seed
>
> > I didn't thought this change would be that tricky, thank you guys for
> these warnings and your help ;)
> Yup, this is a lot of work.
>
> Cheers
> -----------------
> Aaron Morton
> Freelance Cassandra Consultant
> New Zealand
>
> @aaronmorton
> http://www.thelastpickle.com
>
> On 23/04/2013, at 7:26 PM, Alain RODRIGUEZ <arodrime@gmail.com> wrote:
>
> > Hi,these advice are very welcome.
> >
> > @Dane, about the rack awareness, we use only one rack per DC, so I guess
> using EC2MultiRegionSnitch will do just fine and it doesn't need any
> configuration. Does it seem right to you. If we are someday interested on
> multi racks I will make sure to use them properly. Thank you for this
> insight anyway. You are advising me to test it, what would be a good way of
> testing it (I can use AWS EC2 instances if needed) ?
> >
> > @Aaron
> >
> > "I recommend using the same number of nodes in both DC's."
> >
> > Why ? I mean we have maybe only 5% of our customers on the us-east zone,
> what in C* require to have the same number of node on each DC ?
> >
> > "Add the nodes (I recommend 6) with auto_bootstrap: false added to the
> yaml.
> > update the keyspace replication strategy to add rf:3 for the new DC.
> > Use nodetool rebuild on the new nodes to rebuild them from the us-west
> DC. "
> >
> > What is better on adding nodes with no data and then rebuild them
> compared to using the auto_bootstrap ?
> >
> > "I prefer to use the offset method. Take the 6 tokens from your us-west
> DC and add 100 to them for the new dc. "
> >
> > Any doc on this ? I am not aware of all the possibilities. Why is this
> the best method according to you ?
> >
> > About seeds => "Yes. Have 3 from each."
> >
> > What is the point of this ?
> >
> > I didn't thought this change would be that tricky, thank you guys for
> these warnings and your help ;)
> >
> > Alain
> >
> >
> > 2013/4/23 Dane Miller <dane@optimalsocial.com>
> > On Thu, Apr 18, 2013 at 7:41 AM, Alain RODRIGUEZ <arodrime@gmail.com>
> wrote:
> > > I am wondering about the process to grow from one data center to a few
> of
> > > them. First thing is we use EC2Snitch for now. So I guess we have to
> switch
> > > to Ec2MultiRegionSnitch.
> > >
> > > c/ I am using the SimpleStrategy. Is it worth it/mandatory to change
> this
> > > strategy when using multiple DC ?
> >
> > I suggest you thoroughly read the datastax documentation on cassandra
> > replication.  The change you are planning is big - make sure to try it
> > in a test environment first.  Also, you might find you don't really
> > need Cassandra's rack aware feature, and can operate using
> > (Gossiping)PropertyFileSnitch.  The rack feature is listed as an
> > "anti-pattern" here:
> > http://www.datastax.com/docs/1.2/cluster_architecture/anti_patterns
> >
> > Here are some recent discussions on this list:
> >
> http://cassandra-user-incubator-apache-org.3065146.n2.nabble.com/migrating-from-SimpleStrategy-to-NetworkTopologyStrategy-tp7586272.html
> >
> http://cassandra-user-incubator-apache-org.3065146.n2.nabble.com/migrating-from-SimpleStrategy-to-NetworkTopologyStrategy-tp7481090.html
> >
> > Dane
> >
>
>

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