Home > Workload Solutions > SAP > Guides > SAP HANA TDI Guides > Dell Validated Solution for SAP HANA TDI Deployments with Dell Metro Node > Registering initiators
When all the HBAs have been made visible to metro node using zoning:
To claim storage volumes for metro node, start by exporting the SAP HANA volumes from the underlying storage array to the metro node appliance. For specific configuration and sizing recommendations, see the configuration guide for the underlying storage array. Then:
The Storage Arrays page is displayed, as shown in the following figure:
Metro node discovers all unclaimed LUNs.
Dell Technologies recommends using meaningful names such as <basename>_HANA_Data_<X> and <basename>_HANA_Log_<X> to distinguish between the LUNs. Rename them later if necessary.
All LUNs are now claimed and available to the metro node appliance.
To create extents from the previously claimed LUNs:
The Review & Finish page is displayed.
For each LUN, an extent with the total capacity of the LUN is created.
To create devices from the extents:
The Select Device Type page appears.
A summary of the created devices appears.
The volumes are now ready to use with SAP HANA.
The combination of virtual volumes, ports, and initiators controls the visibility of the LUNs to the hosts. To create storage views:
At a minimum, Director A ports FC00 and FC01 and Director B ports FC00 and FC01 are required.
The SAP HANA HA features require all LUNs to be exported to all hosts, including the standby host.
The LUN number 0 is usually preserved for boot LUNs and will not be detected when the host SCSI bus is scanned on reboot.
The Review Results page appears.
We created an SAP HANA scale-out system with three worker nodes and one standby node (3+1). In an SAP HANA cluster with four nodes, each node must have access to every SAP HANA device. During SAP HANA startup, the SAP HANA nameserver together with the SAP HANA storage connector fcClient mounts the volumes to the correct SAP HANA node and I/O fencing.
Note: When using the SAP HANA storage connector fcClient, do not automount the device using /etc/fstab.
Correct preparation of the SAP HANA nodes and the SAP HANA global.ini file is required before the SAP HANA installation. This section describes how to prepare the SAP HANA nodes.
This example assumes that the following basic installation and configuration operations are complete on the SAP HANA nodes:
Note: SAP HANA can only be installed on certified server hardware. A certified SAP HANA expert must perform the installation.
The remainder of this section describes how to configure the metro node virtual volumes for Linux native multipathing and initialize the SAP HANA persistence.
Linux native multipathing (DM-MPIO)
The SLES and Red Hat Enterprise Linux native MPIO already contains default configuration parameters for metro node virtualized storage to provide optimal performance in most environments. Unless you want to modify the default behavior and parameters, it is not necessary to create a multipath.conf file for metro node. When multipathing is enabled, the host accesses the block LUNs over multiple paths, providing redundancy if there is a component failure.
The /etc/multipath.conf file controls multipathing. This file does not exist by default. To view or edit the multipath.conf settings, create the file by running the following command:
multipath -t > /etc/multipath.conf
Note: For the operating system version and storage array MPIO configuration settings for native multipathing, see the Dell EMC Host Connectivity Guide for Linux.
Initialize the SAP HANA persistence
The SAP HANA persistence must be visible to every node in the SAP HANA cluster. Use the rescan-scsi-bus.sh command or reboot each node.
To verify that the volumes are visible, run the following commands on one of the nodes:
1. To list all 768 GB data volumes, type:
multipath -ll | grep -B1 -A5 768G
The following figure shows the command results for one metro node virtual volume.
2. To list all 256 GB log volumes, type:
multipath -ll | grep -B1 -A5 256G
The following figure shows some of the command results.
The unique device identifier of the multipath device must match the WWN of the volumes that you created for metro node in Dell Unisphere. When viewed on a Linux host, the WWN of the volume from the metro node is now preceded by the number 3.
3. Initialize the devices and create the Linux XFS file system on each of the devices:
mkfs.xfs /dev/mapper/ 360001440000000102000519f04b4b597
After you have created all the file systems on all the devices, install the SAP HANA cluster. The following section describes the settings that are required in the SAP HANA global.ini file for an SAP HANA scale-out installation on metro node.
Deploying an SAP HANA multinode scale-out cluster on FC-connected systems requires the SAP HANA storage connector (either fcClient or fcClientMpath). The storage connector is responsible for mounting and unmounting the persistence (data and log) to the SAP HANA worker nodes.
The storage connector writes SCSI-3 persistent reservations (PRs) to the devices. The Linux sg_persist or mpathpersist command initiates an operation known as
“I/O fencing,” which ensures that only one SAP HANA worker host has simultaneous access to a set of data and log devices.
With SAP HANA SP05 Rev 53, SAP released a newer version of the storage connector fcClientMpath. This version of fcClientMpath uses the mpathpersist command instead of the sg_persist command. The main difference between the two commands is that mpathpersist puts the reservations on the devices, enabling device paths to be added while the mount process is ongoing, whereas sg_persist puts the reservations on the device paths when mounting the devices. Paths cannot be added during the mount process, and a remount is necessary.
To use the fcClientMpath connector:
The keys are added during the mount process to /etc/multipath/prkeys.