Detail
We do have fabric connections which usually will be static and are used for intra node communication for replica writes, proxies, duplicate resolution, migrations, meta data exchange and various other intra-cluster record operation.We often see these lines in the logs relevant to this.
Jul 20 2024 12:30:43 GMT: INFO (info): (ticker.c:319) fds: proto (169,3188,3019) heartbeat (3,12,9) fabric (72,72,0) .. Jul 20 2024 12:30:43 GMT: INFO (info): (ticker.c:354) fabric-bytes-per-second: bulk (0,0) ctrl (0,0) meta (160056,106496) rw (32382,36013)This is a 4 nodes cluster and here we see 72 total open connections on this node. The details of which are here.
https://aerospike.com/docs/server/reference/server-log?search=fabric&context=all&version=7&severity=all#info__999762509
What are these 72 fabric connections and how much does each node open to other nodes?
Answer
The answer is each node opens 24 connections to all the other nodes in the cluster. So it will be 24 * (n-1) where n is the cluster-size.The 24 connections are further categorised as below.
- channel-bulk-fds - 2 (x 2 for each direction) = 4
- channel-ctrl-fds - 1 (x 2 for each direction) = 2
- channel-meta-fds - 1 (x 2 for each direction) = 2
- channel-rw-fds - 8 (x 2 for each direction) = 16