SAP NetWeaver Enqueue Replication 1 High Availability Cluster - SAP NetWeaver 7.40 and 7.50 on Alibaba Cloud #

This guide details how to:

This guide focuses on the high availability of the central services.

For SAP HANA system replication, follow the guides for the performance- or cost-optimized scenario.

This guide describes how to set up a pacemaker cluster using SUSE Linux Enterprise Server for SAP Applications 15 for the Enqueue Replication scenario on Alibaba Cloud. The goal is to match the SAP NW-HA-CLU 7.50 (former version 7.40) certification specifications and goals.

These goals include:

The updated certification SAP NW-HA-CLU 7.50 (former version 7.40) has redefined some of the test procedures and described new expectations how the cluster should behave in special conditions. These changes allowed us to improve the cluster architecture and to design it for easier usage and setup.

Shared SAP resources are on a central NFS server.

The SAP instances themselves are installed on a shared disk to allow switching over the file systems for proper functionality. The second need for a shared disk is that we are using the SBD for the cluster fencing mechanism STONITH.

3.2 Three systems for ASCS, ERS, database and additional SAP instances #

 

This guide describes the installation of a distributed SAP system on three systems. In this setup, only two systems are in the cluster. The database and SAP dialog instances could also be added to the cluster by either adding the third node to the cluster or by installing the database on either of the nodes. However we recommend to install the database on a separate cluster.

Note

The cluster in this guide only manages the SAP instances ASCS and ERS, because of the focus of the SAP NW-HA-CLU 7.50 (former version 7.40) certification.

If your database is SAP HANA, we recommend to set up the performance-optimized system replication scenario using our automation solution SAPHanaSR. The SAPHanaSR automation should be set up in an own two node cluster. The setup is described in a separate best practices document available at http://documentation.suse.com/sbp/sap. In case of using ASE database together with an HADR setup, there is an example in this document.

Figure 1: Three systems for the certification setup #

 

Clustered machines #

 

• one machine (sapapp1) for ASCS

  • Host name: vsapascs

• one machine (sapapp2) for ERS

  • Host name: vsapers

Non-Clustered machine #

 

• one machine (sapdb1) for DB and DI

3.3 High availability for the database #

 

Depending on your needs you can also increase the availability of the database if your database is not already highly available by design.

3.3.1 SAP HANA system replication #

 

A perfect enhancement of the three node scenario described in this document is to implement an SAP HANA system replication (SR) automation.

Figure 2: One cluster for central services, one for SAP HANA SR #

 

The following Databases are supported in combination with this scenario:

• SAP HANA DATABASE 1.0

• SAP HANA DATABASE 2.0

3.3.2 ASE database replication #

 

The picture below shows a solution for an ASE HADR setup. The ASE has its own HA mechanism which is managed by Fault Manager. The Fault Manager itself is a single point of failure. The implementation as integrated service or as a separate SAP instance in the Pacemaker cluster for the central services solves this weakness.

Figure 3: One cluster for the central services and the ASE database HADR solution #

 

The following databases are supported in combination with this scenario:

• ASE16 SP03 PL07 onwards

3.3.3 Simple stack #

 

Another option is to implement a second cluster for a database without SR aka "ANYDB". The cluster resource agent SAPDatabase uses the SAPHOSTAGENT to control and monitor the database.

Figure 4: One cluster for the central services and one cluster for the ANY database #

 

Table 1: The following OS / Databases combination are examples for this scenario #

 

SUSE Linux Enterprise Server for SAP Applications 15
Intel X86_64	POWER LITTLE ENDIAN
SAP HANA DATABASE 1.0
SAP HANA DATABASE 2.0	SAP HANA DATABASE 2.0
DB2 FOR LUW 11.5
MaxDB 7.9
ORACLE 12.2
SAP ASE 16.0 FOR BUS. SUITE

Note

The first version for SAP NetWeaver on Power Little Endian is 7.50. More information about supported combinations of OS and databases for SAP NetWeaver can be found at the SAP Product Availability Matrix. (SAP PAM)

3.4 Integration of SAP NetWeaver into the cluster using the Cluster Connector #

 

The integration of the HA cluster through the SAP control framework using the sap_suse_cluster_connector is of special interest. The sapstartsrv controls SAP instances since SAP Kernel versions 6.40. One of the classical problems running SAP instances in a highly available environment is the following:

If an SAP administrator changes the status (start/stop) of an SAP instance without using the interfaces provided by the cluster software, the cluster framework will detect that as an error status. Therefore it will bring the SAP instance into the old status by either starting or stopping the SAP instance. This can result in very dangerous situations if the cluster changes the status of an SAP instance during some SAP maintenance tasks. This new updated solution enables the central component sapstartsrv to report state changes to the cluster software, and therefore avoids the previously described dangerous situations. (See also blog article "Using sap_vendor_cluster_connector for interaction between cluster framework and sapstartsrv") (https://blogs.sap.com/2014/05/08/using-sapvendorclusterconnector-for-interaction-between-cluster-framework-and-sapstartsrv/comment-page-1/).

Figure 5: Cluster connector to integrate the cluster with the SAP start framework #

 

Note

For this scenario we are using an updated version of the sap-suse-cluster-connector. This version implements the API version 3 for the communication between the cluster framework and the sapstartsrv.

The new version of the sap-suse-cluster-connector now allows to start, stop and 'move' an SAP instance. The integration between the cluster software and the sapstartsrv also implements the option to run checks of the HA setup using either the command line tool sapcontrol or the SAP management consoles (SAP MMC or SAP MC).

The next sections contain information about how to prepare your Alibaba Cloud infrastructure.

4.2 Creating VPC #

 

First, create a VPC via Console→Virtual Private Cloud→VPCs→Create VPC. In this example, a VPC named ASEHADR in the Region EU Central 1 (Frankfurt) has been created:

There should be at least two VSwitches (subnets) defined within the VPC network. Each VSwitch should be bound to a different Zone. In this example, the following two VSwitches (subnets) are defined:

• Switch1 "vs_a" 192.168.1.0/24 Zone A, for SAP HANA Primary Node;

• Switch2 "vs_b" 192.168.2.0/24 Zone B, for SAP HANA Secondary Node;

4.3 Creating ECS instances #

 

Four ECS instances are created in different Zones of the same VPC via

Console→Elastic Compute Service ECS→Instances→Create Instance.

Choose the "SUSE Linux Enterprise Server for SAP Applications" image from the Image Market place.

In this example, two ECS instances (host name: sapapp1 and sapdb1) are created in the Region EU Central 1, Zone A , within the VPC: ASEHADR, with SUSE Linux Enterprise Server for SAP Applications 15 SP1 image from the Image Market Place. In contrast, two ECS instances (host name: sapapp2 and sapdb2) are created in the Region EU Central 1, Zone B , within the VPC: ASEHADR, with SUSE Linux Enterprise Server for SAP Applications 15 SP1 image from the Image Market Place.

4.5 Creating STONITH device and virtual IP ResourceAgent #

 

To download and install the components of the following steps, the instance needs to be able to access Internet. The easiest way is to purchase an Elastic IP (https://www.alibabacloud.com/product/eip) and assign it to the instance and unassign it when the configuration is done. For an HA solution, a fencing device is an essential requirement. Alibaba Cloud provides its own STONITH device, which allows the servers in the HA cluster to shut down the node that is not responsive. The STONITH device leverages Alibaba Cloud OpenAPI underneath the ECS instance, which is similar to a physical reset / shutdown in an on-premise environment.

# curl https://raw.githubusercontent.com/ClusterLabs/fence-agents/master/agents/aliyun/fence_aliyun.py > /usr/sbin/fence_aliyun
## Add permission
# chmod 755 /usr/sbin/fence_aliyun
# chown root:root /usr/sbin/fence_aliyun
## set python
# sed -i "1s|@PYTHON@|$(which python)|" /usr/sbin/fence_aliyun
## set Fence agents lib directory
# sed -i "s|@FENCEAGENTSLIBDIR@|/usr/share/fence|" /usr/sbin/fence_aliyun
## Installation verification
# stonith_admin -I |grep fence_aliyun
##  return fence_aliyun as correct
100 devices found
# fence_aliyun

The next component to install is Virtual IP Resource Agent (aliyun-vpc-move-ip). By changing the routing entries, it enables a non-overlapping, private IP addresses to be used as a virtual IP resources in an HA solution.

# mkdir -p /usr/lib/ocf/resource.d/aliyun
# curl https://raw.githubusercontent.com/ClusterLabs/resource-agents/master/heartbeat/aliyun-vpc-move-ip > /usr/lib/ocf/resource.d/aliyun/vpc-move-ip
# chmod 755 /usr/lib/ocf/resource.d/aliyun/vpc-move-ip
# chown root:root /usr/lib/ocf/resource.d/aliyun/vpc-move-ip

Install Alibaba Cloud OpenAPI SDK:

# pip install aliyun-python-sdk-core aliyun-python-sdk-vpc aliyun-python-sdk-ecs

Install Alibaba Cloud CLI:

# wget https://github.com/aliyun/aliyun-cli/releases/download/v3.0.65/aliyun-cli-linux-3.0.65-amd64.tgz
# tar -xvf aliyun-cli-linux-3.0.65-amd64.tgz
# mv aliyun /usr/local/bin

Configure Alibaba Cloud RAM role to authenticate Alibaba Cloud CLI (aliyun) to create OpenAPI operation call.

Login Alibaba Cloud console → Resource Access Management (RAM) → Permissions → Policies

Create a customer policy named “SAP-HA-ROLE-POLICY” with the following content:

{
    "Version": "1",
    "Statement": [
        {
            "Effect": "Allow",
            "Action": [
                "ecs:StartInstance",
                "ecs:StopInstance",
                "ecs:RebootInstance",
                "ecs:Describe*"
            ],
            "Resource": [
                "*"
            ],
            "Condition": {}
        },
        {
            "Effect": "Allow",
            "Action": [
                "vpc:CreateRouteEntry",
                "vpc:DeleteRouteEntry",
                "vpc:Describe*"
            ],
            "Resource": [
                "*"
            ],
            "Condition": {}
        }
    ]
}

Create a RAM role “SAP-HA-ROLE” and assign above RAM policy to it.

Assign above RAM role to the instance we created:

Login Alibaba Cloud console → Elastic Computer Service → Instances → Select the instance → More → Instance Settings → Bind/Unbind RAM role:

Configure Alibaba Cloud OpenAPI SDK and CLI:

# aliyun configure --profile ecsRamRoleProfile --mode EcsRamRole
Configuring profile 'ecsRamRoleProfile' in 'EcsRamRole' authenticate mode...
Ecs Ram Role []: SAP-HA-ROLE
Default Region Id []: eu-central-1
Default Output Format [json]: json (Only support json)
Default Language [zh|en] en:
Saving profile[ecsRamRoleProfile] ...Done.
Configure Done!!!
..............888888888888888888888 ........=8888888888888888888D=..............
...........88888888888888888888888 ..........D8888888888888888888888I...........
.........,8888888888888ZI: ...........................=Z88D8888888888D..........
.........+88888888 ..........................................88888888D..........
.........+88888888 .......Welcome to use Alibaba Cloud.......O8888888D..........
.........+88888888 ............. ************* ..............O8888888D..........
.........+88888888 .... Command Line Interface(Reloaded) ....O8888888D..........
.........+88888888...........................................88888888D..........
..........D888888888888DO+. ..........................?ND888888888888D..........
...........O8888888888888888888888...........D8888888888888888888888=...........
............ .:D8888888888888888888.........78888888888888888888O ..............

• cs Ram Role []: — Input the RAM role created above

• Default Region Id []: — Input current region-ID

4.6 Disks and partitions #

 

For all SAP file systems beside the file systems on NFS we are using XFS.

4.6.1 Shared disk for cluster ASCS and ERS #

 

Create two NAS storage via:

Console→nas→File System List→Create File System→General Purpose NAS(Pay-as-you-go)

In this example following two NAS have been created:

Afterward, execute the below command to mount the created NAS storage to sapapp1:

# mkdir /usr/sap/SSA/ASCS00
# mount 114b194b126-tkt51.eu-central-1.nas.aliyuncs.com:/ /usr/sap/SSA/ASCS00

Afterward, execute the below command to mount the created NAS storage to sapapp2:

# mkdir /usr/sap/SSA/ERS10
# mount 11e5134833f-dlk6.eu-central-1.nas.aliyuncs.com:/ /usr/sap/SSA/ERS10

The mount points are like this:

• sapapp1:

  • 114b194b126-tkt51.eu-central-1.nas.aliyuncs.com:/ /usr/sap/SSA/ASCS00

• sapapp2:

  • 11e5134833f-dlk6.eu-central-1.nas.aliyuncs.com:/ /usr/sap/SSA/ERS10

4.6.2 Disk for DB and dialog instances (ASE DB example) #

 

The disk for the database and primary application server is assigned to sapdb1. In an advanced setup this disk should be shared between sapdb1 and an optional additional node building an own cluster.

To be mounted either by OS or an optional cluster #

 

• sapdb1: /dev/vdc /sybase/SSA/srsdata

• sapdb1: /dev/sdb3 /usr/sap/SSA/DVEBMGS01

• sapdb1: /dev/sdb4 /usr/sap/SSA/D02

Note

D01 ⇒ Since SAP NetWeaver 7.5, the primary application server instance directory has been renamed. (D<Instance_Number>)

In our example, we use block storage for database storage. Execute the below command on node sapdb1:

# mkdir /sybase/SSA/srsdata
# echo /dev/vdc /sybase/SSA/srsdata ext4 acl,user_xattr,noatime 1 1 >> /etc/fstab

Installation Media. The installation media are normally store in a central place which can be mounted from all node which need the software. We normally mount this share or export to /sapcd.

192.168.1.123  sapapp1
192.168.2.92  sapapp2
192.168.1.124  sapdb1
192.168.4.11  vsapascs
192.168.5.11  vsapers

4.8 Mount points and NFS shares #

 

In our setup the directory /usr/sap is part of the root file system. You could of course also create a dedicated file system for that area and mount /usr/sap during the system boot. As /usr/sap also contains the SAP control file sapservices and the saphostagent, the directory should not be placed on a shared file system between the cluster nodes.

We need to create the directory structure on all nodes which might be able to run the SAP resource. The SYS directory will be on an NFS share for all nodes.

• Creating mount points and mounting NFS share on all nodes

Example 1: SAP NetWeaver 7.5 #

 

# mkdir -p /sapmnt
# mkdir -p /usr/sap/SSA/{ASCS00,D01,D02,ERS10,SYS}
# mount -t nfs :1189b8484a0-pwo18.eu-central-1.nas.aliyuncs.com:/    /sapmnt
# mount -t nfs :11c2284a122-fjk10.eu-central-1.nas.aliyuncs.com:/ /usr/sap/SSA/SYS

• Only ASEDB: creating mount points for the database at sapdb1:

# mkdir -p /sybase/SSA/srsdata

• Only HANA: creating mount points for database at sapdb1:

# mkdir -p /hana/{shared,data,log}

• Other databases: creating mount points based on there installation guide.

As we do not control the NFS shares via the cluster in this setup, you should add these file systems to /etc/fstab to get the file systems mounted during the next system boot.

Figure 6: File system layout including NFS shares #

 

We prepare the three servers for the distributed SAP installation. Server 1 (sapapp1) will be used to install the ASCS SAP instance. Server 2 (sapapp2) will be used to install the ERS SAP instance. Server 3 (sapdb1) will be used to install the dialog SAP instances and the database.

• Mounting the instance and database file systems at one specific node:

Example 2: SAP NetWeaver 7.50 on x86_64 architecture with ASEDB #

 

(ASCS   sapapp1) # mount 114b194b126-tkt51.eu-central-1.nas.aliyuncs.com:/ /usr/sap/SSA/ASCS00
(ERS    sapapp2) # mount 11e5134833f-dlk6.eu-central-1.nas.aliyuncs.com:/ /usr/sap/SSA/ERS10
(DB     sapdb1) # mount /dev/vdc /sybase/SSA/srsdata
(Dialog sapdb1) # mount /dev/sdb3 /usr/sap/SSA/D01
(Dialog sapdb1) # mount /dev/sdb4 /usr/sap/SSA/D02

• As a result, the directory /usr/sap/SSA/ should now look as follows:

# ls -la /usr/sap/SSA/
total 0
drwxr-xr-x 1 ssaadm sapsys 70 28. Mar 17:26 ./
drwxr-xr-x 1 root   sapsys 58 28. Mar 16:49 ../
drwxr-xr-x 7 ssaadm sapsys 58 28. Mar 16:49 ASCS00/
drwxr-xr-x 1 ssaadm sapsys  0 28. Mar 15:59 D02/
drwxr-xr-x 1 ssaadm sapsys  0 28. Mar 15:59 D01/
drwxr-xr-x 1 ssaadm sapsys  0 28. Mar 15:59 ERS10/
drwxr-xr-x 5 ssaadm sapsys 87 28. Mar 17:21 SYS/

Note

The owner of the directory and files is changed during the SAP installation. By default all of them are owned by root.

The overall procedure to install the distributed SAP is:

The result will be a distributed SAP installation as illustrated here:

Figure 7: Distributed installation of the SAP system #

 

5.1 Linux user and group number scheme #

 

Whenever asked by the SAP software provisioning manager (SWPM) which Linux User IDs or Group IDs to use, refer to the following table which is, of course, only an example.

Group sapinst      1000
Group sapsys       1001
Group sapadm       3000
Group sdba         3002

User  ssaadm       3000
User  sdb          3002
User  sqdssa       3003
User  sapadm       3004

Note

Adapt the value as you like. These are examples and may not fit into your company policy.

5.2 Installing ASCS on sapapp1 #

 

Temporarily we need to set the service IP address used later in the cluster as local IP, because the installer wants to resolve or use it. Make sure to use the right virtual host name for each installation step. Take care of the ASCS file systems like 114b194b126-tkt51.eu-central-1.nas.aliyuncs.com:/ and /sapcd/ (where the installation sources live) which might also need to be mounted.

# ip a a 192.168.4.11/24 dev eth0
# mount 114b194b126-tkt51.eu-central-1.nas.aliyuncs.com:/ /usr/sap/SSA/ASCS00
# cd /sapcd/SWPM/
# ./sapinst SAPINST_USE_HOSTNAME=vsapascs

• SWPM option depends on SAP NetWeaver version and architecture

  • Installing SAP NetWeaver AS for ABAP 7.52 → SAP ASE → Installation → Application Server ABAP → High-Availability System → ASCS Instance

• SID id SSA

• Use instance number 00

• Deselect using FQDN

• All passwords: use <yourSecurePwd>

• Double-check during the parameter review, if virtual name vsapascs is used

Note

Adapt the values, for example SID ID, instance number, virtual host name, etc. These are examples and may not fit into your company policy.

5.3 Installing ERS on sapapp2 #

 

Temporarily we need to set the service IP address used later in the cluster as local IP, because the installer wants to resolve or use it. Make sure to use the right virtual host name for each installation step.

# ip a a 192.168.5.11/24 dev eth0
# mount 11e5134833f-dlk6.eu-central-1.nas.aliyuncs.com:/ /usr/sap/SSA/ERS10
# cd /sapcd/SWPM/
# ./sapinst SAPINST_USE_HOSTNAME=vsapers

• SWPM option depends on SAP NetWeaver version and architecture

  • Installing SAP NetWeaver AS for ABAP 7.52 → SAP ASE → Installation → Application Server ABAP → High-Availability System → Enqueue Replication Server Instance

• Use instance number 10

• Deselect using FQDN

• Double-check during the parameter review if virtual name vsapers is used

• If you get an error during the installation about permissions, change the ownership of the ERS directory

Note

Adapt the values, for example SID ID, instance number, virtual host name, etc. These are examples and may not fit into your company policy.

# chown -R ssaadm:sapsys /usr/sap/SSA/ERS10

• If you get a prompt to manually stop/start the ASCS instance, log in to sapapp1 as user ssaadm and call sapcontrol.

# sapcontrol -nr 00 -function Stop    # to stop the ASCS
# sapcontrol -nr 00 -function Start   # to start the ASCS

5.4 Post-steps for ASCS and ERS #

 

5.4.1 Stopping ASCS and ERS #

 

On sapapp1

# su - ssaadm
# sapcontrol -nr 00 -function Stop
# sapcontrol -nr 00 -function StopService

On sapapp2

# su - ssaadm
# sapcontrol -nr 10 -function Stop
# sapcontrol -nr 10 -function StopService

5.4.2 Maintaining sapservices #

 

Ensure /usr/sap/sapservices hold both entries (ASCS+ERS) on both cluster nodes. This allows the sapstartsrv clients to start the service like (do not execute this at this point in time).

As user ssaadm, do:

# sapcontrol -nr 10 -function StartService SSA

The /usr/sap/sapservices looks like (typically one line per instance):

#!/bin/sh
LD_LIBRARY_PATH=/usr/sap/SSA/ASCS00/exe:$LD_LIBRARY_PATH; export LD_LIBRARY_PATH; /usr/sap/SSA/ASCS00/exe/sapstartsrv pf=/usr/sap/SSA/SYS/profile/SSA_ASCS00_vsapascs -D -u ssaadm
LD_LIBRARY_PATH=/usr/sap/SSA/ERS10/exe:$LD_LIBRARY_PATH; export LD_LIBRARY_PATH; /usr/sap/SSA/ERS10/exe/sapstartsrv pf=/usr/sap/SSA/ERS10/profile/SSA_ERS10_vsapers -D -u ssaadm

5.4.3 Integrating the cluster framework using sap-suse-cluster-connector #

 

Install the package sap-suse-cluster-connector version 3.1.x from our repositories on both cluster nodes:

# zypper in sap-suse-cluster-connector

Note

Be careful there are two packages available. The package sap_suse_cluster_connector continues to contain the old version 1.1.0 (SAP API 1). The package sap-suse-cluster-connector contains the new version 3.1.x (SAP API 3). The package sap-suse-cluster-connector with version 3.1.x implements the SUSE SAP API version 3. New features like SAP Rolling Kernel Switch (RKS) and the migration of ASCS are only supported with this new version.

For the ERS and ASCS instance edit the instance profiles SSA_ASCS00_vsapascs and SSA_ERS10_vsapers in the profile directory /usr/sap/SSA/SYS/profile/.

You need to tell the sapstartsrv to load the HA script connector library and to use the sap-suse-cluster-connector.

service/halib = $(DIR_EXECUTABLE)/saphascriptco.so
service/halib_cluster_connector = /usr/bin/sap_suse_cluster_connector

Add the user ssaadm to the unix user group haclient.

# usermod -aG haclient ssaadm

5.4.4 Adapting SAP profiles to match the SAP NW-HA-CLU 7.50 (former version 7.40) certification #

 

For the ASCS, change the start command from Restart_Programm_xx to Start_Programm_xx for the enqueue server (enserver). This change tells the SAP start framework not to self-restart the enqueue process. Such a restart would lead in loss of the locks.

Example 3: File /usr/sap/SSA/SYS/profile/SSA_ASCS00_vsapascs #

 

Start_Program_01 = local $(_EN) pf=$(_PF)

Optionally you could limit the number of restarts of services (in the case of ASCS this limits the restart of the message server).

For the ERS change instance the start command from Restart_Programm_xx to Start_Programm_xx for the enqueue replication server (enrepserver).

Example 4: File /usr/sap/SSA/SYS/profile/SSA_ERS10_vsapers #

 

Start_Program_00 = local $(_ER) pf=$(_PFL) NR=$(SCSID)

5.4.5 Starting ASCS and ERS #

 

On sapapp1

# su - ssaadm
# sapcontrol -nr 00 -function StartService SSA
# sapcontrol -nr 00 -function Start

On sapapp2

# su - ssaadm
# sapcontrol -nr 10 -function StartService SSA
# sapcontrol -nr 10 -function Start

# cd /<path to the SWPM>/
# ./sapinst

# ip a a 192.168.1.118/24 dev eth0
# mount /dev/sdb3 /usr/sap/SSA/D01
# cd /sapcd/SWPM/
# ./sapinst SAPINST_USE_HOSTNAME=sapssad1

# ip a a 192.168.1.119/24 dev eth0
# mount /dev/sdb4 /usr/sap/SSA/D02
# cd /sapcd/SWPM/
# ./sapinst SAPINST_USE_HOSTNAME=sapssad2

The main procedure to implement the cluster is as follows:

Note

The SBD device/partition need to be created in beforehand. In this setup guide we do not use the SBD device.

# zypper in -t pattern ha_sles

# ha-cluster-init -y -i eth0 -u

# ha-cluster-join -y -c 192.168.1.123 -i eth0

Last updated: Thu Nov 21 14:25:53 2019		Last change: Thu Nov 21 14:23:21 2019 by ssaadm via crm_resource on sapapp1
Stack: corosync
Current DC: sapapp1 (version 1.1.19-20181105.ccd6b5b10) - partition with quorum
2 nodes configured

Online: [ sapapp1 sapapp2 ]

# crm configure show
...
property cib-bootstrap-options: \
        have-watchdog=false \
        dc-version="2.0.1+20190417.13d370ca9-3.9.1-2.0.1+20190417.13d370ca9" \
        cluster-infrastructure=corosync \
        cluster-name=hacluster \
        stonith-enabled=true \
        last-lrm-refresh=1494346532
rsc_defaults rsc-options: \
        resource-stickiness=1 \
        migration-threshold=3
op_defaults op-options: \
        timeout=600 \
        record-pending=true

6.2 Configuring cluster resources #

 

We need a changed SAPInstance resource agent for SAP NetWeaver to not use the master-slave construct anymore. This also implies a move to a more cluster-like construct to start and stop the ASCS and the ERS themselves and not only the complete master-slave.

To get there, there is a new functionality for the ASCS needed to follow the ERS. The ASCS needs to mount the shared memory table of the ERS to avoid the loss of locks.

Figure 8: Resources and constraints #

 

The implementation is done using the new flag "runs_ers_$SID" within the RA, enabled with help of the resource parameter "IS_ERS=TRUE".

Another benefit of this concept is that we can now work with local (mountable) file systems instead of a shared (NFS) file system for the SAP instance directories.

6.2.1 Preparing the cluster for adding the resources #

 

To avoid that the cluster starts partially defined resources, we set the cluster to the maintenance mode. This deactivates all monitor actions.

As user root, do:

# crm configure property maintenance-mode="true"

6.2.2 Configuring the Stonith resources for an Alibaba Cloud infrastructure #

 

Alibaba Cloud provides its own STONITH device, which allows the servers in the HA cluster to shut down the other which is not responsible. The STONITH device leverage Alibaba Cloud OpenAPI underneath the ECS instance, which is similar to a physical reset / shutdown on a on-premise environment."

Example 5: Alibaba Cloud fencing agent #

 

primitive res_ALIYUN_STONITH_1 stonith:fence_aliyun \
	op monitor interval=120 timeout=60 \
	params plug=i-gw87xi82sj2dy2ysaw19 ram_role=SAP-HA-ROLE region=eu-central-1 \
	meta target-role=Started
primitive res_ALIYUN_STONITH_2 stonith:fence_aliyun \
	op monitor interval=120 timeout=60 \
	params plug=i-gw86pnh1jy1dw0vfer3w ram_role=SAP-HA-ROLE region=eu-central-1 \
	meta target-role=Started

Example 6: Stonith location rules #

 

location loc_sapapp1_stonith_not_on_sapapp1 res_ALIYUN_STONITH_1 -inf: sapapp1
location loc_sapapp2_stonith_not_on_sapapp2 res_ALIYUN_STONITH_2 -inf: sapapp2

Create a txt file (like crm_stonith.txt) with your preferred text editor, enter both examples (primitives and location rules) to that file and load the configuration to the cluster manager configuration.

As user root, do:

# crm configure load update crm_stonith.txt

6.2.3 Configuring the resources for the ASCS #

 

First we configure the resources for the file system, IP address and the SAP instance. Of course you need to adapt the parameters to your environment.

Example 7: ASCS primitive #

 

primitive rsc_fs_SSA_ASCS00 Filesystem \
  params device="114b194b126-tkt51.eu-central-1.nas.aliyuncs.com:/" directory="/usr/sap/SSA/ASCS00" \
     fstype=nfs \
  op start timeout=60s interval=0 \
  op stop timeout=60s interval=0 \
  op monitor interval=20s timeout=40s
primitive rsc_ip_SSA_ASCS00 ocf:aliyun:vpc-move-ip \
  params ip=192.168.4.11 routing_table=vtb-gw8irrnvm8vd29iji5ufk endpoint=vpc-vpc.eu-central-1.aliyuncs.com interface=eth0 \
  op monitor interval=10s timeout=20s
primitive rsc_sap_SSA_ASCS00 SAPInstance \
  operations $id=rsc_sap_SSA_ASCS00-operations \
  op monitor interval=11 timeout=60 on-fail=restart \
  params InstanceName=SSA_ASCS00_vsapascs \
     START_PROFILE="/sapmnt/SSA/profile/SSA_ASCS00_vsapascs" \
     AUTOMATIC_RECOVER=false \
  meta resource-stickiness=5000 failure-timeout=60 \
     migration-threshold=1 priority=10

Example 8: ASCS group #

 

group grp_SSA_ASCS00 \
  rsc_ip_SSA_ASCS00 rsc_fs_SSA_ASCS00 rsc_sap_SSA_ASCS00 \
     meta resource-stickiness=3000

Create a txt file (like crm_ascs.txt) with your preferred text editor, enter both examples (primitives and group) to that file and load the configuration to the cluster manager configuration.

As user root, do:

# crm configure load update crm_ascs.txt

6.2.4 Configuring the resources for the ERS #

 

Second, we configure the resources for the file system, IP address and the SAP instance. Of course you need to adapt the parameters to your environment.

The specific parameter IS_ERS=true should only be set for the ERS instance.

Example 9: ERS primitive #

 

primitive rsc_fs_SSA_ERS10 Filesystem \
  params device="11e5134833f-dlk6.eu-central-1.nas.aliyuncs.com:/" directory="/usr/sap/SSA/ERS10" fstype=nfs \
  op start timeout=60s interval=0 \
  op stop timeout=60s interval=0 \
  op monitor interval=20s timeout=40s
primitive rsc_ip_SSA_ERS10 ocf:aliyun:vpc-move-ip \
  params ip=192.168.5.11 routing_table=vtb-gw8irrnvm8vd29iji5ufk endpoint=vpc-vpc.eu-central-1.aliyuncs.com interface=eth0 \
  op monitor interval=10s timeout=20s
primitive rsc_sap_SSA_ERS10 SAPInstance \
  operations $id=rsc_sap_SSA_ERS10-operations \
  op monitor interval=11 timeout=60 on-fail=restart \
  params InstanceName=SSA_ERS10_vsapers \
     START_PROFILE="/sapmnt/SSA/profile/SSA_ERS10_vsapers" \
     AUTOMATIC_RECOVER=false IS_ERS=true \
  meta priority=1000

Example 10: ERS group #

 

group grp_SSA_ERS10 \
  rsc_ip_SSA_ERS10 rsc_fs_SSA_ERS10 rsc_sap_SSA_ERS10

Create a txt file (like crm_ers.txt) with your preferred text editor, enter both examples (primitives and group) to that file and load the configuration to the cluster manager configuration.

As user root, do:

# crm configure load update crm_ers.txt

6.2.5 Configuring the colocation constraints between ASCS and ERS #

 

The constraints between the ASCS and ERS instance are needed to define that the ASCS instance starts exactly on the cluster node running the ERS instance after a failure (loc_sap_SSA_fail-over_to_ers). This constraint is needed to ensure that the locks are not lost after an ASCS instance (or node) failure.

If the ASCS instance has been started by the cluster the ERS instance should be moved to an "other" cluster node (col_sap_SSA_no_both). This constraint is needed to ensure that the ERS will synchronize the locks again and the cluster is ready for an additional take-over.

Example 11: Location constraint #

 

colocation col_sap_SSA_no_both -5000: grp_SSA_ERS10 grp_SSA_ASCS00
location loc_sap_SSA_fail-over_to_ers rsc_sap_SSA_ASCS00 \
         rule 2000: runs_ers_SSA eq 1
order ord_sap_SSA_first_start_ascs Optional: rsc_sap_SSA_ASCS00:start \
      rsc_sap_SSA_ERS10:stop symmetrical=false

Create a txt file (like crm_col.txt) with your preferred text editor, enter all three constraints to that file and load the configuration to the cluster manager configuration.

As user root, do:

# crm configure load update crm_col.txt

6.2.6 Activating the cluster #

 

Now the last step is to end the cluster maintenance mode and to allow the cluster to detect already running resources.

As user root, do:

# crm configure property maintenance-mode="false"

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