First, note that replication is done at the row level, not at the node level.
That line should look more like:
placement_strategy = 'NetworkTopologyStrategy' and strategy_options = {DC1:
1,DC2: 1,DC3: 1 }
This means that each row will have one copy in each DC and within each DC it's
Thanks!
My missunderstanding was the snitch names are broken up by DC1:RAC1
and the strategy_options takes only the first part of the snitch
names?
On Wed, May 30, 2012 at 12:14 PM, Jeff Williams
je...@wherethebitsroam.com wrote:
First, note that replication is done at the row level, not at
You can avoid the confusion by using the term natural endpoints. For
example, with a replication factor of 3 natural endpoints for key x
are node1, node2, node11.
The snitch does use the datacenter and the rack but almost all
deployments use a single rack per DC, because when you have more then
On May 30, 2012, at 10:32 PM, Edward Capriolo wrote:
The snitch does use the datacenter and the rack but almost all
deployments use a single rack per DC, because when you have more then
one rack in a data center the NTS snitch has some logic to spread the
data between racks. (most people
http://answers.oreilly.com/topic/2408-replica-placement-strategies-when-using-cassandra/
As mentioned it does this:
The Network Topology Strategy places some replicas in another data
center and the remainder in other racks in the first data center, as
specified
Which is not what most would
Ok now i am confused :),
ok if i have the following
placement_strategy = 'NetworkTopologyStrategy' and strategy_options =
{DC1:R1,DC2:R1,DC3:R1 }
this means in each of my datacenters i will have one full replica that
also can be seed node?
if i have 3 node in addition to the DC replica's with
This is partly historical. NTS (as it is now) has not always existed and was
not always the default. In days gone by used to be a fella could run a mighty
fine key-value store using just a Simple Replication Strategy.
A different way to visualise it is a single ring with a Z axis for the DC's.
Now if a row key hash is mapped to a range owned by a node in DC3,
will the Node in DC3 still store the key as determined by the
partitioner and then walk the ring and store 2 replicas each in DC1
and DC2 ?
No, only nodes in the DC's specified in the NTS configuration will be replicas.
Or
Thanks Aaron. That makes things clear.
So I guess the 0 - 2^127 range for tokens corresponds to a cluster
-level top-level ring. and then you add some logic on top of that with
NTS to logically segment that range into sub-rings as per the notion
of data clusters defined in NTS. Whats the advantage
Hi all,
I am a bit confused regarding the terms replica and
replication factor. Assume that I am using RandomPartitioner and
NetworkTopologyStrategy for replica placement.
From what I understand, with a RandomPartitioner, a row key will
always be hashed and be stored on the node that
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