Hinted handoffs - how do they work?

[Paul T <pa...@yahoo.com>]

Good morning!
I have a been reading through Cassandra wiki and have some confusion around how 
hinted handoffs work.

Here is my scenario:
Five nodes in the ring (A, B, C, D, E)
Replication factor=3
Assume that the replicas for a given key are A, B, C
Assume CL=ONE 

During a write operation, nodes  B and C are down.
Will hints for B and C be written to just A (the only live replica available) or 
will D and E also take the hints and the data?  

If D and E take on the hints+data, will that data be reachable during a 
subsequent read operation? (assuming B and C are still down)

Would appreciate a clarification.
TIA


      

Re: Hinted handoffs - how do they work?

[Jonathan Ellis <jb...@gmail.com>]

On Sat, Feb 5, 2011 at 6:46 AM, Paul T <pa...@yahoo.com> wrote:
> Good morning!
> I have a been reading through Cassandra wiki and have some confusion around
> how hinted handoffs work.
> Here is my scenario:
> Five nodes in the ring (A, B, C, D, E)
> Replication factor=3
> Assume that the replicas for a given key are A, B, C
> Assume CL=ONE
> During a write operation, nodes  B and C are down.
> Will hints for B and C be written to just A (the only live replica
> available)

Just A.

-- 
Jonathan Ellis
Project Chair, Apache Cassandra
co-founder of DataStax, the source for professional Cassandra support
http://www.datastax.com