Takeover not occurring as expected in SAP HANA environment on Azure

This document (000019610) is provided subject to the disclaimer at the end of this document.

Environment

SUSE Linux Enterprise Server for SAP Applications
SUSE Linux Enterprise High Availability Extension
Microsoft Azure

Situation

There are many reasons why a node in a SAP HANA scale-out or scale-up cluster will not takeover as expected. One such reason may be due to the stickiness of the netcat/socat/azure-lb resource. This stickiness can prevent a takeover from occurring because the resource favors the host where it is currently running. This situation can occur if resource-stickiness is not explicitly specified in the netcat/socat/azure-lb resource as shown:

primitive nc_NW1_nfs anything \
  params binfile="/usr/bin/nc" cmdline_options="-l -k 61000" \
  op monitor timeout=20s interval=10 depth=0

primitive rsc_nc_HN1_HDB03 anything \
   params binfile="/usr/bin/socat" cmdline_options="-U TCP-LISTEN:61000,backlog=10,fork,reuseaddr /dev/null" \
   op monitor timeout=20s interval=10

primitive rsc_nc_HN1_HDB03 azure-lb port=61000 \
   op monitor timeout=20s interval=10

Resolution

Explicitly specify a resource-stickiness=0 to the resource as shown:

primitive nc_NW1_nfs anything \
  params binfile="/usr/bin/nc" cmdline_options="-l -k 61000" \
  op monitor timeout=20s interval=10 depth=0 \
  meta resource-stickiness=0

primitive rsc_nc_HN1_HDB03 anything \
   params binfile="/usr/bin/socat" cmdline_options="-U TCP-LISTEN:61000,backlog=10,fork,reuseaddr /dev/null" \
   op monitor timeout=20s interval=10 \
   meta resource-stickiness=0

primitive rsc_nc_HN1_HDB03 azure-lb port=61000 \
   op monitor timeout=20s interval=10 \
   meta resource-stickiness=0

Cause

The stickiness of the resource can prevent a takeover from occurring because the resource favors the host where it is currently running.

Disclaimer

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Document ID:000019610
Creation Date: 04-May-2020
Modified Date:08-May-2020
- SUSE Linux Enterprise High Availability Extension
- SUSE Linux Enterprise Server for SAP Applications

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