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Subject: Re: Replication Factor and Data Centers
From: Jeremy Hanna <jeremy.hanna1234@gmail.com>
In-Reply-To: <AANLkTikcEW3IuONJcBbZBLjkpfKcQJb3aQy2NAOITYOi@mail.gmail.com>
Date: Tue, 15 Jun 2010 13:01:03 -0500
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To: dev@cassandra.apache.org


On Jun 15, 2010, at 12:43 AM, Masood Mortazavi wrote:

> Is the clearer interpretation of this statement (in
> conf/datacenters.properties) given anywhere else?
>=20
> # The sum of all the datacenter replication factor values should equal
> # the replication factor of the keyspace (i.e. sum(dc_rf) =3D RF)
>=20
> # keyspace\:datacenter=3Dreplication factor
> Keyspace1\:DC1=3D3
> Keyspace1\:DC2=3D2
> Keyspace1\:DC3=3D1
>=20
> Does the above example configuration imply that Keyspace1 has a RF of =
6, and
> that of these 3 will go to DC1, 2 to DC2 and 1 to DC3?
>=20

Yes, that's the idea.

> What will happen if datacenters.properties and =
cassandra-rack.properties are
> simply empty?
>=20

It will throw a configuration exception if the properties files are not =
there.  There may be changes to how this is done before 0.7 is finalized =
though.  For example the configuration files may be turned into simple =
thrift calls like what is being done with the dynamic keyspace =
configuration.=20

> - m.