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SETUP TWO NODE HANA CLUSTER WITH REPLICATION AND HIGH AVAILABILITY

Suse Linux

SETUP TWO NODE HANA CLUSTER WITH REPLICATION AND HIGH AVAILABILITY


This document is to basically provide a guide for people who wants to install HANA on SLES for SAP to test out solutions like Trento and HANA monitoring in SUSE Manager.
While working with MSP, they look for similar solutions in our documentation. From a production view we should ask them to follow SAP guidelines, however this document provides a starting point to understand the overall solution for educational and testing purposes.

In this blog we will see step by step implementation process of a 2-Node HANA DB with site replication along with SUSE High availability solutions.

Please Note:
SAP HANA SPS07 rev.073 is known to have issues. It should not be used, better to use rev.078 at least (even if you disable encryption).
SAPHanaSR is deprecated. For new installations, SAPHanaSR-angi should be used.
Reference Official Documents:
https://documentation.suse.com/sbp/sap-15/html/SLES4SAP-hana-angi-perfopt-15/index.html

 

System Landscape:

  • Node 1:
    IP: 192.168.211.42
    Hostname: hana-n1
  • Node 2:
    IP: 192.168.211.43
    Hostname: hana-n2
  • HAWK Console VIP: 192.168.211.45
  • Iscsi/NFS Server: 192.168.211.41
  • HANA SID: HA1
  • HANA Instance: 10
  • Site 1: WDF
  • Site 2: ROT

 

Pre-Requisites:

  • SLES for SAP installed with below mentioned partitions on 2 nodes.
  • Iscsi server has been configured and a 2 GB disk shared as Iscsi targets on both nodes for SBD.
  • Optional: Multipath configured and alias for Iscsi disk set properly for consistency.
  • Required Local Partitions: (The size mentioned here are for testing purpose and actual production deployment sizes may vary)
    • /hana/data      – 50 G
    • /hana/shared – 20 G
    • /hana/log        – 50 G
    • /usr/sap           – 10 G
    • Optional: NFS Partition /data
    • iSCSI partition for SBD: 1 GB

 

SAP Installation

Download and unzip files

Download the files for SAP download center and place them on both servers.

I have used a /data NFS partition mounted on both servers.

 

Start the Installation

Node 1:

Navigate to HDB_SERVER_LINUX_X86_64 directory and execute hdblcm binary to start the installation

cd sap_inst/DATA_UNITS/HDB_SERVER_LINUX_X86_64
./hdblcm

  • Select Option 1 to start install

  • Select 2 for Components
  • Keep Defaults where ever mentioned

  • For System Usage Select Production. Option 1.
  • It will not affect the resource consumption, so you can select any.
  • Select No for Encryption
  • Enter Passwords as required.
  • For DB Password it should have 1 upper case.
  • Post the reboot option it will give you a summary as below

  • If all is good select yes.
  • Once finished you should get the below output:

Node 2:

Once installation is finished repeat the same steps on Node 2 with same SID and Instance Number as on Node 1

 

Setting up Replication

Reference: Follow the official documentation starting from Point No.7

On Node 1: Login with ha1adm user and Backup the Database:

su - ha1adm
hdbsql -i 10 -u SYSTEM -d SYSTEMDB "BACKUP DATA FOR FULL SYSTEM USING FILE ('backup')"

Enable the Primary Node “node 1”:

hdbnsutil -sr_enable --name=WDF

Check SR on Node 1

hdbnsutil -sr_stateConfiguration --sapcontrol=1

On the Second Node stop the Hana DB:

HDB stop

Copy the KEY and KEY-DATA file from the primary to the secondary site:

On Node2:

cd /usr/sap/HA1/SYS/global/security/rsecssfs/
scp 192.168.211.42:/usr/sap/HA1/SYS/global/security/rsecssfs/data/SSFS_HA1.DAT data/
scp 192.168.211.42:/usr/sap/HA1/SYS/global/security/rsecssfs/key/SSFS_HA1.KEY key/

Now Register the second Node:

hdbnsutil -sr_register --name=ROT --remoteHost=hana-n1 --remoteInstance=10 --replicationMode=sync --operationMode=logreplay

Start Secondary and Check SR Configuration

HDB start

Check Replication Status

hdbnsutil -sr_stateConfiguration --sapcontrol=1

Note that the mode is “SYNC”

Further details on replication can be found using the script hdbsettings:

HDBSettings.sh systemReplicationStatus.py --sapcontrol=1

Configuring Replication, Takeover, checksrv hooks and ha1adm user access to cluster

Follow the below step in Both Nodes.

Edit the global.ini file and enter the below parameters

vim /hana/shared/HA1/global/hdb/custom/config/global.in

[ha_dr_provider_saphanasr]
provider = SAPHanaSR
path = /usr/share/SAPHanaSR/
execution_order = 1

[trace]
ha_dr_saphanasr = info

[ha_dr_provider_sustkover]
provider = susTkOver
path = /usr/share/SAPHanaSR/
execution_order = 2

[trace]
ha_dr_sustkover = info

[ha_dr_provider_suschksrv]
provider = susChkSrv
path = /usr/share/SAPHanaSR/
execution_order = 3
action_on_lost=stop

[trace]
ha_dr_suschksrv = info

Also make sure the [system_replication] section has the operation mode parameter defined as logreplay

[system_replication]
mode = primary
actual_mode = primary
site_id = 1
site_name = WDF
operation_mode = logreplay

The file should look like this:

On Node1:

On Node 2:

Configure ha1adm user access to cluster on both nodes:

Create a new file SAPHanaSR in suders.d and add the below content:

vim /etc/sudoers.d/SAPHanaSR
# SAPHanaSR-ScaleUp entries for writing srHook cluster attribute and SAPHanaSR-hookHelper
ha1adm ALL=(ALL) NOPASSWD: /usr/sbin/crm_attribute -n hana_ha1_site_srHook_*
ha1adm ALL=(ALL) NOPASSWD: /usr/sbin/SAPHanaSR-hookHelper *

Check the newly configured hooks

Start HANA in both server using below command:

HDB start

Once started check the hooks are loaded properly using cdtrace

cdtrace
grep HADR.*load.*SAPHanaSR nameserver_*.trc
grep SAPHanaSR.init nameserver_*.trc
grep HADR.*load.*susTkOver nameserver_*.trc
grep susTkOver.init nameserver_*.trc
grep HADR.*load.*susChkSrv nameserver_*.trc
grep susChkSrv.init nameserver_*.trc
egrep '(LOST:|STOP:|START:|DOWN:|init|load|fail)' nameserver_suschksrv.trc
grep SAPHanaSR.srConnection.*CRM nameserver_*.trc
grep SAPHanaSR.srConnection.*fallback nameserver_*.trc

Check Replication:

SAPHanaSR-showATTR

Setup High Availability

To setup ha please have SBD configured on both nodes.

For this setup I have used multipath for consistency.

Configure Multipath

Please Note: This step is completely optional and direct UUID or ID can be used from “(/dev/disk/by-uuid/<uuid>)” or “”(/dev/disk/by-id/<ID>)” and directly put in to “/etc/sysconfig/sbd” and the same has been referenced in our documentation.

If you choose to configure multipath continue with below steps or else jump straight to HA installation point post making entry of disk ID in the above config

First make sure you have an Iscsi server which exposes a device of 2 GB as Iscsi target.

In both nodes make sure Iscsi client is configured and connected.

Refer the official guide for help here:

You should be able to see the device in

fdisk -l

Next install multipath if not already installed

zypper install multipath*

Start and enable multipathd.service.

systemctl enable multipathd.service
systemctl start multipathd.service

Start and enable chronyd.service.

systemctl enable chronyd.service
systemctl start chronyd.service

Generate the multipath configuration file using the command

multipath -T >/etc/multipath.conf

This command should automatically configure multipath for the sbd device, however alias won’t be added.

Edit the multipath.conf file and add the alias for the device.

Reload multipath:

service multipathd reload

New device should be available in

fdisk -l

This is the device we will use in HA configuration.

Repeat the steps on Node 2

HA installation

Initiate HA installation on Node1

ha-cluster-init -U -s /dev/mapper/mpath-sbd

Answer “No” for VIP and QDevice.

Some commands to check if SBD has been configured correctly:

egrep -v "(^#|^$)" /etc/sysconfig/sbd
sbd -d /dev/mapper/mpath-sbd dump
sbd -d /dev/mapper/mpath-sbd list

Please Note:

“ha-cluster-init” creates too short SBD msgwait by default. So assign a suitable value that is aligned with iSCSI and MPIO timings.

On second Node to join this cluster:

ha-cluster-join -c 192.168.211.42

To check the cluster: (On both nodes):

systemctl status pacemaker
systemctl status sbd
crm cluster start
crm status

SAP Cluster Configuration

The Below steps are to be done only on one of the nodes, typically the master node or node 1.

Now that the initial cluster is setup lets configure SAP HANA multistate using separate configuration files and loading it into cluster.

The syntax would be as below:

vi crm-fileXX
crm configure load update crm-fileXX

Cluster bootstrap

vi crm-bs.txt
###
# enter the following to crm-bs.txt
property cib-bootstrap-options: 
stonith-enabled="true" 
stonith-action="reboot" 
stonith-timeout="150" 
priority-fencing-delay="30"
rsc_defaults rsc-options: 
resource-stickiness="1000" 
migration-threshold="5000"
op_defaults op-options: 
timeout="600" 
record-pending=true

Load config to cluster:

crm configure load update crm-bs.txt

STONITH device

vi crm-sbd.txt
###
# enter the following to crm-sbd.txt
primitive stonith-sbd stonith:external/sbd 
params pcmk_delay_max="15"

Load config to cluster:

crm configure load update crm-sbd.txt

SAPHanaTopology

vi crm-saphanatop.txt
###
# enter the following to crm-saphanatop.txt
primitive rsc_SAPHanaTop_HA1_HDB10 ocf:suse:SAPHanaTopology 
op monitor interval="10" timeout="600" 
op start interval="0" timeout="600" 
op stop interval="0" timeout="300" 
params SID="HA1" InstanceNumber="10"
clone cln_SAPHanaTop_HA1_HDB10 rsc_SAPHanaTop_HA1_HDB10 
meta clone-node-max="1" interleave="true"

Load config to cluster:

crm configure load update crm-saphanatop.txt

SAPHana

vi crm-saphana.txt
# enter the following to crm-saphana.txt
primitive rsc_SAPHana_HA1_HDB10 ocf:suse:SAPHana 
op start interval="0" timeout="3600" 
op stop interval="0" timeout="3600" 
op promote interval="0" timeout="3600" 
op monitor interval="60" role="Master" timeout="700" 
op monitor interval="61" role="Slave" timeout="700" 
params SID="HA1" InstanceNumber="10" PREFER_SITE_TAKEOVER="true" 
DUPLICATE_PRIMARY_TIMEOUT="7200" AUTOMATED_REGISTER="false" 
meta priority="100"
ms msl_SAPHana_HA1_HDB10 rsc_SAPHana_HA1_HDB10 
meta clone-max="2" clone-node-max="1" interleave="true" maintenance=true

Load config to cluster:

crm configure load update crm-saphana.txt

Virtual IP address

# vi crm-vip.txt
# enter the following to crm-vip.txt
primitive rsc_ip_HA1_HDB10 ocf:heartbeat:IPaddr2 
op monitor interval="10s" timeout="20s" 
params ip="192.168.211.45"

Load config to cluster:

crm configure load update crm-vip.txt

Constraints for SAPHanaSR

#vim crm-cs.txt
# enter the following to crm-cs.txt
colocation col_saphana_ip_HA1_HDB10 2000: rsc_ip_HA1_HDB10:Started 
msl_SAPHana_HA1_HDB10:Master
order ord_SAPHana_HA1_HDB10 Optional: cln_SAPHanaTop_HA1_HDB10 
msl_SAPHana_HA1_HDB10

Load config to cluster:

crm configure load update crm-cs.txt

Activating multi-state resource for cluster operation

crm resource refresh msl_SAPHana_HA1_HDB10
crm resource maintenance msl_SAPHana_HA1_HDB10 off

That’s it you successfully configured HANA with replication and HA.

If you go to your HAWK portal, you should see as below:

Check Replication and Cluster Status:

Testing

Test 1:

HDB stop
  • Automatic take over should happen and node 2 should be promoted.
  • Refresh cluster resource and check status
crm resource refresh rsc_SAPHana_HA1_HDB10 hana-n1
crm status
  • Node 1 should start and stay as secondary

To Recover:

hdbnsutil -sr_register --name=WDF --remoteHost=hana-n2 --remoteInstance=10 --replicationMode=sync --operationMode=logreplay

Test 2:

HDB stop
  • Automatic take over should happen and node 1 should be promoted

hdbnsutil -sr_register --name=ROT --remoteHost=hana-n1 --remoteInstance=10 --replicationMode=sync --operationMode=logreplay
  • Node 2 should start and stay as secondary

If you are facing issue to start HANA, try clearing constraints in HA console once.

Appendix

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