4 ms·

I don't think this is the case - check this link: https://knowledgebase.progress.com/articles/Article/expected-latency-between-aws-availability-zones https://kn

I don't think this is the case - check this link: https://knowledgebase.progress.com/articles/Article/expected-latency-between-aws-availability-zones https://knowledgebase.progress.com/articles/Article/expected... The intra AZ latency according to AWS is sub millisecond! It's inline with what our customers see. Since all of the numbers in the blog are above a millisecond, the result does not change.

otterley 8y ago
Intra-AZ latency is indeed sub-millisecond. Inter-AZ latency is in the milliseconds range. (The intra prefix means within, inter means between.) And those latencies accumulate quickly when benchmarking. Why don't you try it yourself and see the difference? Relying on some third party website is no substitute for testing.
- thekozmo 8y ago
  I went and run a ping between 2 VMs, one on us-east1c and the other on a different AZ - us-east-1b As you can see, the ping latency is 0.5ms to 1ms on rare occasions. Of course that ping has a cost even within a single AZ so the above numbers reflect much more than the AZ round trip time. You're welcome to add 1ms to our latency numbers, it's 3x-4x better in the 99th case so there's enough room... 64 bytes from 35.173.249.24: icmp_seq=14 ttl=63 time=0.584 ms 64 bytes from 35.173.249.24: icmp_seq=15 ttl=63 time=0.462 ms 64 bytes from 35.173.249.24: icmp_seq=16 ttl=63 time=0.848 ms 64 bytes from 35.173.249.24: icmp_seq=17 ttl=63 time=0.465 ms 64 bytes from 35.173.249.24: icmp_seq=18 ttl=63 time=0.451 ms 64 bytes from 35.173.249.24: icmp_seq=19 ttl=63 time=1.00 ms 64 bytes from 35.173.249.24: icmp_seq=20 ttl=63 time=0.854 ms 64 bytes from 35.173.249.24: icmp_seq=21 ttl=63 time=0.446 ms
  - erik_seaberg 8y ago
    Inter-AZ latency is going to matter more for conditional writes. I'm disappointed to find LWT so far out on Scylla's roadmap since preventing conflicts is a showstopper for correctness and we found it to be Cassandra's weak point in scaling.
    - jjirsa 8y ago
      fwiw, work being done on Cassandra to speed this (cas/lwt) up SIGNIFICANTLY
      - ddorian43 8y ago
        Link ?
        jjirsa 8y ago
        Started here: https://lists.apache.org/thread.html/15d1b4b5bb8a24e41d51db58538b56d0bab40c17fc9c64e898f2ad3b@%3Cdev.cassandra.apache.org%3E https://lists.apache.org/thread.html/15d1b4b5bb8a24e41d51db5... Continues here: https://issues.apache.org/jira/browse/CASSANDRA-14448 https://issues.apache.org/jira/browse/CASSANDRA-14448

otterley 8y ago

Intra-AZ latency is indeed sub-millisecond. Inter-AZ latency is in the milliseconds range. (The intra prefix means within, inter means between.) And those latencies accumulate quickly when benchmarking. Why don't you try it yourself and see the difference? Relying on some third party website is no substitute for testing.

thekozmo 8y ago
I went and run a ping between 2 VMs, one on us-east1c and the other on a different AZ - us-east-1b As you can see, the ping latency is 0.5ms to 1ms on rare occasions. Of course that ping has a cost even within a single AZ so the above numbers reflect much more than the AZ round trip time. You're welcome to add 1ms to our latency numbers, it's 3x-4x better in the 99th case so there's enough room... 64 bytes from 35.173.249.24: icmp_seq=14 ttl=63 time=0.584 ms 64 bytes from 35.173.249.24: icmp_seq=15 ttl=63 time=0.462 ms 64 bytes from 35.173.249.24: icmp_seq=16 ttl=63 time=0.848 ms 64 bytes from 35.173.249.24: icmp_seq=17 ttl=63 time=0.465 ms 64 bytes from 35.173.249.24: icmp_seq=18 ttl=63 time=0.451 ms 64 bytes from 35.173.249.24: icmp_seq=19 ttl=63 time=1.00 ms 64 bytes from 35.173.249.24: icmp_seq=20 ttl=63 time=0.854 ms 64 bytes from 35.173.249.24: icmp_seq=21 ttl=63 time=0.446 ms
- erik_seaberg 8y ago
  Inter-AZ latency is going to matter more for conditional writes. I'm disappointed to find LWT so far out on Scylla's roadmap since preventing conflicts is a showstopper for correctness and we found it to be Cassandra's weak point in scaling.
  - jjirsa 8y ago
    fwiw, work being done on Cassandra to speed this (cas/lwt) up SIGNIFICANTLY
    - ddorian43 8y ago
      Link ?
      - jjirsa 8y ago
        Started here: https://lists.apache.org/thread.html/15d1b4b5bb8a24e41d51db58538b56d0bab40c17fc9c64e898f2ad3b@%3Cdev.cassandra.apache.org%3E https://lists.apache.org/thread.html/15d1b4b5bb8a24e41d51db5... Continues here: https://issues.apache.org/jira/browse/CASSANDRA-14448 https://issues.apache.org/jira/browse/CASSANDRA-14448