RF is normally adjusted to modify availability (see http://thelastpickle.com/2011/06/13/Down-For-Me/)
> for example, if I have 4 nodes cluster in one data center, how can RF=2 vs RF=4 affect
read performance? If consistency level is ONE, looks reading does not need to go to another
hop to get data if RF=4, but it would do more work on read repair in the background.
Read Repair does not run at CL ONE.
When RF == number of nodes, and you read at CL ONE you will always be reading locally. But
with a low consistency.
If you read with QUORUM when RF == number of nodes you will still get some performance benefit
from the data being read locally.
Cheers
-----------------
Aaron Morton
Freelance Developer
@aaronmorton
http://www.thelastpickle.com
On 23/05/2012, at 9:34 AM, Daning Wang wrote:
> Hello,
>
> What is the pros and cons to choose different number of replication factor in term of
performance? if space is not a concern.
>
> for example, if I have 4 nodes cluster in one data center, how can RF=2 vs RF=4 affect
read performance? If consistency level is ONE, looks reading does not need to go to another
hop to get data if RF=4, but it would do more work on read repair in the background.
>
> Can you share some insights about this?
>
> Thanks in advance,
>
> Daning
>
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