Re: Number of DCs in Cassandra

2021-07-14 Thread Jeff Jirsa
Hi, So, there's two things where you'll see the impact of "lots of datacenters" On the query side, global quorum queries (and queries with cross-dc probabilistic read repair) may touch more DCs and be slower, and read-repairs during those queries get more expensive. Your geography matters a ton f

Re: Number of DCs in Cassandra

2021-07-14 Thread Shaurya Gupta
Hi, Multiple DCs are required to maintain lower latencies for requests across the globe. I agree that it's a lot of redundant copies of data. On Wed, Jul 14, 2021, 7:00 PM Jim Shaw wrote: > Shaurya: > What's the purpose to partise too many data centers ? > RF=3, is within a center, you have 3

Re: Number of DCs in Cassandra

2021-07-14 Thread Jim Shaw
Shaurya: What's the purpose to partise too many data centers ? RF=3, is within a center, you have 3 copies of data. If you have 3 DCs, means 9 copies of data. Think about space wasted, Network bandwidth wasted for number of copies. BTW, Ours just 2 DCs for regional DR. Thanks, Jim On Wed, Jul 1

Re: Number of DCs in Cassandra

2021-07-14 Thread manish khandelwal
Reading and writing with local_quorum should not be a problem in terms of performance if all data centers are healthy. But Quorum queries will take hit due to network latency and that is expected and I believe you are aware of that. On Wed, Jul 14, 2021 at 12:38 PM Shaurya Gupta wrote: > We are

Re: Number of DCs in Cassandra

2021-07-14 Thread Shaurya Gupta
We are planning to go with 5 DCs with RF of 3 in each. All DCs will have reads and writes. Most queries are done at LOCAL_QUORUM. A very few Simple and CAS queries (<0.1%) will be done at QUORUM consistency. On Wed, Jul 14, 2021 at 12:19 PM manish khandelwal < manishkhandelwa...@gmail.com> wrote: