Hi Folks, In one of our big cluster, due to capacity increase, more servers are added to the cluster, and we saw from many pserver reporting error message below: "neighbour: ndisc_cache: neighbor table overflow!"
We've tested increasing the gc_thresh values in sysctl.conf, after reboot, the errors are gone +# Threshold when garbage collector becomes more aggressive about +# purging entries. Entries older than 5 seconds will be cleared +# when over this number. Default: 512 +net.ipv4.neigh.default.gc_thresh2 = 4096 +net.ipv6.neigh.default.gc_thresh2 = 4096 + +# Maximum number of non-PERMANENT neighbor entries allowed. Increase +# this when using large numbers of interfaces and when communicating +# with large numbers of directly-connected peers. Default: 1024 +net.ipv4.neigh.default.gc_thresh3 = 8192 +net.ipv6.neigh.default.gc_thresh3 = 8192 But we still have many systems running in production, so my question is: is it safe to apply the setting on the fly when servers are running with busy traffic? or we have to apply the setting only through sysctl during boot? Most of our servers with default settings are running kernel 4.14.137~4.14.154 Thanks in advance! Best regards! Jack Wang
