Hallo Jeff,
very interesting stuff, thank you for sharing!
Indeed, I am storing time-series data. The table has 67 columns. Writing is
done in two steps: First 43 fields (3 primary key fields and 40 data fields)
than 27 fields (3 primary key fields and 24 data fields) in a second step,
always
There's a small amount of overhead on each packet for serialization - e.g.,
each mutation is tied to a column family (uuid) and gets serialized with
sizes and checksums, so I guess there's a point where your updates are
small enough that the overhead of the mutations starts being visible.
You
Hi Scott,
Thank you for your help. There was an error or at least an ambiguity in my
second Mail! I wrote:
I still see outgoing cross-DC traffic of ~ 2x the “write size A”
What I wanted to say was: I still see outgoing cross-DC traffic of ~ 2x the
“write size A” per remote DC or 4x the
2x makes sense tho. If you have 3 DCs, you write locally to DC1 and then it
gets replicated once in DC1 and then it gets replicated to DC2 AND DC3 at
consistency local_one via cross DCtraffic to one of the nodes in each DC,
then replicated in each DC to a second node via local traffic
Write comes
Hi,
I checked for all the given other factors - anti entropy repair, hints, read
repair - and I still see outgoing cross-DC traffic of ~ 2x the “write size A”
(as defined below). Given Jeffs answers this is not to be expected, i.e. there
is something wrong here. Does anybody have an idea how
Hi Jeff,
Thank you for your answer, very helpful already!
All writes are done with `LOCAL_ONE` and we have RF=2 in each data center.
To compare our examples we need to come to an agreement on what you are calling
“write size A”. I gave two different write sizes:
I call the bandwidth for
> On Nov 26, 2020, at 9:53 AM, Jens Fischer wrote:
>
> Hi,
>
> we run a Cassandra cluster with three DCs. We noticed that the traffic
> incurred by running the Cluster is significant.
>
> Consider the following simplified IoT scenario:
>
> * time series data from devices in the field is
Hi,
we run a Cassandra cluster with three DCs. We noticed that the traffic incurred
by running the Cluster is significant.
Consider the following simplified IoT scenario:
* time series data from devices in the field is received at Node A
* Node A inserts the data into DC 1
* DC 1 replicates
