Prepare the target host
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This section describes the preparation steps required at the server that is used for the disaster recovery failover.
During normal operation, the target host is typically used for other purposes, for example, as a HANA QA or test system. Therefore, most of the described steps must be executed when disaster failover testing is executed. On the other hand, the relevant configuration files, like /etc/fstab and /usr/sap/sapservices, can be prepared and then put in production by simply copying the configuration file. The disaster recovery failover procedure ensures that the relevant prepared configuration files are configured correctly.
The target host preparation also includes shutting down the HANA QA or test system as well as stopping all services using systemctl stop sapinit.
Target server host name and IP address
The host name of the target server must be identical to the host name of the source system. The IP address can be different.
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Proper fencing of the target server must be established so that it cannot communicate with other systems. If proper fencing is not in place, then the cloned production system might exchange data with other production systems, resulting in logically corrupted data. |
Install required software
The SAP host agent software must be installed at the target server. For full information, see the SAP Host Agent at the SAP help portal.
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If the host is used as a HANA QA or test system, the SAP host agent software is already installed. |
Configure users, ports, and SAP services
The required users and groups for the SAP HANA database must be available at the target server. Typically, central user management is used; therefore, no configuration steps are necessary at the target server. The required ports for the HANA database must be configured at the target hosts. The configuration can be copied from the source system by copying the /etc/services file to the target server.
The required SAP services entries must be available at the target host. The configuration can be copied from the source system by copying the /usr/sap/sapservices file to the target server. The following output shows the required entries for the SAP HANA database used in the lab setup.
vm-pr1:~ # cat /usr/sap/sapservices #!/bin/sh LD_LIBRARY_PATH=/usr/sap/PR1/HDB01/exe:$LD_LIBRARY_PATH;export LD_LIBRARY_PATH;/usr/sap/PR1/HDB01/exe/sapstartsrv pf=/usr/sap/PR1/SYS/profile/PR1_HDB01_vm-pr1 -D -u pr1adm limit.descriptors=1048576
Prepare HANA log volume
Because the HANA log volume is not part of the replication, an empty log volume must exist at the target host. The log volume must include the same subdirectories as the source HANA system.
vm-pr1:~ # ls -al /hana/log/PR1/mnt00001/ total 16 drwxrwxrwx 5 root root 4096 Feb 19 16:20 . drwxr-xr-x 3 root root 22 Feb 18 13:38 .. drwxr-xr-- 2 pr1adm sapsys 4096 Feb 22 10:25 hdb00001 drwxr-xr-- 2 pr1adm sapsys 4096 Feb 22 10:25 hdb00002.00003 drwxr-xr-- 2 pr1adm sapsys 4096 Feb 22 10:25 hdb00003.00003 vm-pr1:~ #
Prepare log backup volume
Because the source system is configured with a separate volume for the HANA log backups, a log backup volume must also be available at the target host. A volume for the log backups must be configured and mounted at the target host.
If log backup volume replication is part of the disaster recovery setup, the replicated log backup volume is mounted at the target host, and it is not necessary to prepare an additional log backup volume.
Prepare file system mounts
The following table shows the naming conventions used in the lab setup. The volume names at the disaster recovery site are included in /etc/fstab.
| HANA PR1 volumes | Volume and subdirectories at disaster recovery site | Mount point at target host |
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Data volume |
PR1-data-mnt00001-sm-dest |
/hana/data/PR1/mnt00001 |
Shared volume |
PR1-shared-sm-dest/shared |
/hana/shared |
Log backup volume |
hanabackup-sm-dest |
/hanabackup |
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The mount points from this table must be created at the target host. |
Here are the required /etc/fstab entries.
vm-pr1:~ # cat /etc/fstab # HANA ANF DB Mounts 10.0.2.4:/PR1-data-mnt0001-sm-dest /hana/data/PR1/mnt00001 nfs rw,vers=4,minorversion=1,hard,timeo=600,rsize=262144,wsize=262144,intr,noatime,lock,_netdev,sec=sys 0 0 10.0.2.4:/PR1-log-mnt00001-dr /hana/log/PR1/mnt00001 nfs rw,vers=4,minorversion=1,hard,timeo=600,rsize=262144,wsize=262144,intr,noatime,lock,_netdev,sec=sys 0 0 # HANA ANF Shared Mounts 10.0.2.4:/PR1-shared-sm-dest/hana-shared /hana/shared nfs rw,vers=4,minorversion=1,hard,timeo=600,rsize=262144,wsize=262144,intr,noatime,lock,_netdev,sec=sys 0 0 10.0.2.4:/PR1-shared-sm-dest/usr-sap-PR1 /usr/sap/PR1 nfs rw,vers=4,minorversion=1,hard,timeo=600,rsize=262144,wsize=262144,intr,noatime,lock,_netdev,sec=sys 0 0 # HANA file and log backup destination 10.0.2.4:/hanabackup-sm-dest /hanabackup nfs rw,vers=3,hard,timeo=600,rsize=262144,wsize=262144,nconnect=8,bg,noatime,nolock 0 0