ESXi host disconnected from the vCenter frequently due to the lack of buffer space for TCPIP

Products

• VMware vSphere ESXi 7.0

Issue/Introduction

TCP IP heap memory exhaustion occurs due to heap fragmentation or low availability of memory.

There could be several symptoms due to lack of memory like ESX host not accessible, failure of some services, PSODs, host disconnects, etc.

Environment

ESXi 7U3n or earlier

Cause

Lack of heap memory due to memory fragmentation and/or configuration restricts memory expansion.

vmkernel will have the below warnings:

YYYY-MM-DDTHH:mm:ss.765Z cpu65:257021746)WARNING: Tcpip: 2420: socreate(type=2, proto=0) failed with error No buffer space available (55)
YYYY-MM-DDTHH:mm:ss.001Z cpu64:257027065)WARNING: Tcpip: 2420: socreate(type=1, proto=6) failed with error No buffer space available (55)
YYYY-MM-DDTHH:mm:ss.001Z cpu1:257026653)WARNING: Tcpip: 2420: socreate(type=1, proto=6) failed with error No buffer space available (55)
YYYY-MM-DDTHH:mm:ss.919Z cpu3:2098900)WARNING: Tcpip: 2420: socreate(type=1, proto=6) failed with error No buffer space available (55)

Resolution

A fix is available in ESXi 7U3o.

The issue is resolved by improved handling of memory to reduce fragmentation and also provide an option to allow increasing heap memory to a larger value. This will reduce the chances of memory failures.