On 6/22/2011 5:56 PM, mcasandra wrote:
LOCAL_QUORUM gurantees consistency in the local data center only. Other
replica nodes in the same DC and other DC not part of the QUORUM will be
eventually consistent. If you want to ensure consistency accross DCs you can
use EACH_QUORUM but keep in mind the latency involved assuming DCs are not
located within short distance.
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Thanks mcasandra.
I would like to know the minimal consistency_level to assure absolute
consistency with a multiple data center setup for minimal latency. Just
as quorum read/writes is the minimal needed to assure consistency with a
single data center cluster, what is the equivalent read/write
consistency_level value pair with a multi data center environment?
I'm thinking... writes at EACH_QUORUM and reads at LOCAL_QUORUM? This
will handle when a data center gets partitioned. The write will fail
if the dc's get partitioned. If the partition happens after a
successful write, then that's ok and a local quorum is all that's needed
for a subsequent read that's consistent.
