Adding a Resource with Constraints without affecting the existing Resources into a Cluster
This document (7023856) is provided subject to the disclaimer at the end of this document.
Environment
SUSE Linux Enterprise High Availability Extension 12
SUSE Linux Enterprise High Availability Extension 11
SUSE Linux Enterprise High Availability Extension 11
Situation
Assuming there is a setup from a Best Practice Guide, for example a Clustered Hana in Performance optimized Scenario as
killer (stonith:external/sbd): Started oldhanaa1
rsc_ip_HA0_HDB00 (ocf::heartbeat:IPaddr2): Started oldhanaa1
Master/Slave Set: msl_SAPHana_HA0_HDB00 [rsc_SAPHana_HA0_HDB00]
Masters: [ oldhanaa1 ]
Slave: [ oldhanaa2 ]
Clone Set: cln_SAPHanaTopology_HA0_HDB00 [rsc_SAPHanaTopology_HA0_HDB00]
Started: [ oldhanaa1 oldhanaa2 ]
with
property cib-bootstrap-options: \
have-watchdog=true \
dc-version="1.1.19+20180928.0d2680780-1.8-1.1.19+20180928.0d2680780" \
cluster-infrastructure=corosync \
cluster-name=theben \
stonith-timeout=28 \
last-lrm-refresh=1557221612
rsc_defaults rsc-options: \
resource-stickiness=500 \
migration-threshold=5000
and one wanted to add a MailTo Resource with a colocation to the IP Address to this setup, to get a notification on Resource Change from the cluster via Mail.
primitive rsc_mail MailTo \
params email="root@oldholborn.hwlab.suse.de" subject="Cluster HA0"
colocation col_mailto_ip_HA0_HDB00 inf: rsc_mail rsc_ip_HA0_HDB00
This could potentially lead to the situation that the running setup would be disturbed by the new Resource because of the new constraint.
killer (stonith:external/sbd): Started oldhanaa1
rsc_ip_HA0_HDB00 (ocf::heartbeat:IPaddr2): Started oldhanaa1
Master/Slave Set: msl_SAPHana_HA0_HDB00 [rsc_SAPHana_HA0_HDB00]
Masters: [ oldhanaa1 ]
Slave: [ oldhanaa2 ]
Clone Set: cln_SAPHanaTopology_HA0_HDB00 [rsc_SAPHanaTopology_HA0_HDB00]
Started: [ oldhanaa1 oldhanaa2 ]
with
property cib-bootstrap-options: \
have-watchdog=true \
dc-version="1.1.19+20180928.0d2680780-1.8-1.1.19+20180928.0d2680780" \
cluster-infrastructure=corosync \
cluster-name=theben \
stonith-timeout=28 \
last-lrm-refresh=1557221612
rsc_defaults rsc-options: \
resource-stickiness=500 \
migration-threshold=5000
and one wanted to add a MailTo Resource with a colocation to the IP Address to this setup, to get a notification on Resource Change from the cluster via Mail.
primitive rsc_mail MailTo \
params email="root@oldholborn.hwlab.suse.de" subject="Cluster HA0"
colocation col_mailto_ip_HA0_HDB00 inf: rsc_mail rsc_ip_HA0_HDB00
This could potentially lead to the situation that the running setup would be disturbed by the new Resource because of the new constraint.
Resolution
To resolve this without affecting the running resources one has to make sure, that the new Resource follows the existing resources and not the other way around. In this scenario the use of the
inf:
Value for constraints will be bad and have the effect that the Hana IP fails over to the other node, dragging the Hana Master with it. It is the value of this colocation that is critical for the behaviour of the cluster.
To do this the correct one has to take the resource-stickiness into account, which is defined either per resource or by default in the
rsc_defaults
Section of the cib.
Considering that there is in this example a
resource-stickiness=500
and the constraint between the Master and the IP is 2000 as in
colocation col_saphana_ip_HA0_HDB00 2000: rsc_ip_HA0_HDB00:Started msl_SAPHana_HA0_HDB00:Master
the correct value is higher than 500 but less than 2000.
In this example a working snippet would be
primitive rsc_mail MailTo \
params email="root@oldholborn.hwlab.suse.de" subject="Cluster HA0"
colocation col_mailto_ip_HA0_HDB00 501: rsc_mail rsc_ip_HA0_HDB00
which can be injected with
crm configure load update /path_to_my_snippet_file
inf:
Value for constraints will be bad and have the effect that the Hana IP fails over to the other node, dragging the Hana Master with it. It is the value of this colocation that is critical for the behaviour of the cluster.
To do this the correct one has to take the resource-stickiness into account, which is defined either per resource or by default in the
rsc_defaults
Section of the cib.
Considering that there is in this example a
resource-stickiness=500
and the constraint between the Master and the IP is 2000 as in
colocation col_saphana_ip_HA0_HDB00 2000: rsc_ip_HA0_HDB00:Started msl_SAPHana_HA0_HDB00:Master
the correct value is higher than 500 but less than 2000.
In this example a working snippet would be
primitive rsc_mail MailTo \
params email="root@oldholborn.hwlab.suse.de" subject="Cluster HA0"
colocation col_mailto_ip_HA0_HDB00 501: rsc_mail rsc_ip_HA0_HDB00
which can be injected with
crm configure load update /path_to_my_snippet_file
Cause
Sola dosis facit venenum
Disclaimer
This Support Knowledgebase provides a valuable tool for SUSE customers and parties interested in our products and solutions to acquire information, ideas and learn from one another. Materials are provided for informational, personal or non-commercial use within your organization and are presented "AS IS" WITHOUT WARRANTY OF ANY KIND.
- Document ID:7023856
- Creation Date: 07-May-2019
- Modified Date:03-Mar-2020
-
- SUSE Linux Enterprise High Availability Extension
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