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SAP High Availability in Azure Using SUSE Linux

[BP-1404]

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Agenda

Basic SAP Architecture

SAP HA Architecture in Azure

Pacemaker

Azure Load Balancer

Demo of unplanned failover

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SAP Architecture

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Basic SAP architecture

Application

Server

Database

ServerShared Disk

Central

Services

Database

Storage

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S/4HANA High Availability Architecture in Azure

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Availability Set (99.95%) Availability Zones (99.99%)

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SUSE High

Availability

Extension

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The Goal of HA

MTTR

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SUSE High Availability Overview

corosync (cluster membership)

pacemaker (crm)

Resource Agents (RAs)

Fencing (stonith)

Kernel Kernel

SAP SAPSAP

Storage

(SBD)

vIP vIP

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Resource Agents

Provides ‘intelligence to Pacemaker’

A script used to start/stop/monitor a resource

• Ideally should be Open Cluster Framework compliant

• Well defined return values

• Mandatory operations

• Return value passed back to Pacemaker

• Many providers of RAs

• Ships with around 140 RA out of the box.

• Resource Agents for SAP HANA included in SLES for SAP Applications

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SAP HANA Resource Agents

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Why Do We Need Fencing?

To a cluster node, loss of a peer node is indistinguishable from loss of

communication with that node.

In the former case, is it safe to failover resources?

And in the latter case?

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Split Brain

• When a cluster partitions due to network failure

• Neither side knows if the other is still alive

• Worst case scenario: each side attempts to failover the other's resource

• Better scenario: neither side does anything

(But then, why do we have a cluster?)

• Best scenario: one side is able to guarantee that the other is down

• Fencing is about moving from an UNKNOWN state to a KNOWN state

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SUSE High

Availability with

SAP Central

Services

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Enqueue-Replication Versions

ENSA2ENSA1

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Central Services – Multi SID

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Architecture options for SAP on Azure

File system

• BYO SUSE cluster

• ANF

• NFS (future)

Az availability

options

• Av Set

• Av Zone

Fencing agent

• SBD

• Azure Fencing agent (future)

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Floating IP: Two Basic Architectures Possible

Hana

1

Hana

2

PAS

Azure Load

Balancer

Hana

1

Hana

2

PAS

Floating IP

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Let’s look at the first case

Hana

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Hana

2

PAS

Floating IP

Hana

System

Replication

Sr_takeover

• “Floating” IP can be moved from

one machine to another via

API/CLI

• IP Move takes approximately 2

minutes

24Backend Pool

Load Balancer

Hana

1

Hana

2

Client

Azure Load

Balancer

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Hana

1

Hana

2

PAS

Floating IP

Hana

System

Replication

Sr_takeover

Azure Load

Balancer

Health

Probe

Health

Probe

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SOCAT & Virtual IP Network Resource

sudo crm configure primitive rsc_ip_HN1_HDB03 ocf:heartbeat:IPaddr2 \ meta target-

role="Started" is-managed="true" \ operations \$id="rsc_ip_HN1_HDB03-operations" \

op monitor interval="10s" timeout="20s" \ params ip="10.0.0.13"

sudo crm configure primitive rsc_nc_HN1_HDB03 anything \ params

binfile="/usr/bin/socat" cmdline_options="-U TCP-

LISTEN:62503,backlog=10,fork,reuseaddr /dev/null" \ op monitor timeout=20s

interval=10 depth=0

sudo crm configure group g_ip_HN1_HDB03 rsc_ip_HN1_HDB03 rsc_nc_HN1_HDB03

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Unplanned Failover

Several mechanisms for testing:

• Shut down machine from Azure

portal

• ps aux | grep sbd, kill inquisitor

• service pacemaker stop

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Takeaways

Read the Documentation

Setup & test your configuration and

keep testing

Understand the operations

Monitoring & Alerts

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Resources

Links to documentation

https://documentation.suse.com/sbp/all/

Links to automation

https://github.com/SUSE/ha-sap-

terraform-deployments

Training & certification

https://training.suse.com/training/sap/

Azure training & certifications

[TUT-1226]

SAP HA on SUSE: All you need to know

[TUT-1396]

"Day 2" Operations of SAP HANA Cluster using SUSE High Availability on Public Cloud

[HOL-1064]

SAP HANA scale-out with high availability NFS using DRBD

[BP-1351]

SUSE High Availability for SAP HANA: Tales from the real world, tips, tricks, & troubleshooting

[HOL-1225]

High Availability for SAP application servers using ENSA2 enqueue replication.

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