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From Anthony Ikeda <anthony.ikeda....@gmail.com>
Subject Re: Will writes with < ALL consistency eventually propagate?
Date Mon, 07 Nov 2011 06:11:29 GMT
It's your replication factor that determines how many nodes contain the data. So you would
set the replication factor to 5 to ensure all nodes contain the data. 

Your consistency level is all based on when should the server return to the client after writing.
When one node has written the data (ConsistencyLevel.ONE)? Or when all nodes have been written
to (ConsistencyLevel.ALL)?

Just remember if your replication factor is to ensure all nodes have a copy you may not be
able to survive the loss of a single node. 

Sent from my iPhone

On 06/11/2011, at 21:50, Riyad Kalla <rkalla@gmail.com> wrote:

> I am new to Cassandra and was curious about the following scenario...
> 
> Lets say i have a ring of 5 servers. Ultimately I would like each server to be a full
replication of the next (master-master-*). 
> 
> In a presentation i watched today on Cassandra, the presenter mentioned that the ring
members will shard data and route your requests to the right host when they come in to a server
that doesnt physically contain the value you wanted. To the client requesting this is seamless
excwpt for the added latency.
> 
> If i wanted to avoid the routing and latency and ensure every server had the full data
set, do i have to write with a consistency level of ALL and wait for all of those writes to
return in my code, or can i write with a CL of 1 or 2 and let the ring propagate the rest
of the copies to the other servers in the background after my code has continued executing?
> 
> I dont mind eventual consistency in my case, but i do (eventually) want all nodes to
have all values and cannot tell if this is default behavior, or if sharding is the default
and i can only force duplicates onto the other servers explicitly with a CL of ALL.
> 
> Best,
> Riyad

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