Dear Guru's,

This is Mithran and I have been working as SAP Basis Consultant. I am always eager to learn more in Linux.

I have few queries or information required to get a clear picture of Cluster Setup in SAP.

Suse-Linux is the OS. Pacemaker Cluster, SBD we are using it and everything is running in Azure Cloud.

Below are the setup being used in SAP NW Cluster setup:

1.SAP ASCS and ERS each running different nodes.
2.NFS Servers are also running in cluster setup - 2 nodes for NFS.
3.Adding further we have 3 ISCSI Servers.

SAP ASCS and ERS related Kernel Files, shared files are located in NFS Servers.

Why do we use 3 ISCSI Servers what happens if there is only 2. if 1 iscsi goes down next one will be available, but why 3 instead of 2.

NFS mount points will be coming from ISCSI Storage right which is being monitored by iscsi servers right? how about ASCS and ERS those servers will also be accessing the same iscsi storage of NFS right?

since when i checked below commands
1. lsscsi
2. ls -l /dev/disk/by-id/scsi-* in ASCS/ERS and NFS disk values showed were different, hence got confusion and cluster setup is completely new and i am very eager to learn.

Please do the needful.

Thanks & Regards,
Mithran