SVC Enhanced Stretch Cluster configuration

Example of cabling

In the best recommandations, alternate one port on Fabric SAN A (blue), then a port on B (red)…

Set the port mask to 11, so only ports 1 and 2 are able to communicate in node

SVC:superuser>chsystem -localfcportmask 00001100 

SVC:superuser>lssystem |grep mask
local_fc_port_mask 00000000000000000000000000000000000000000000000000000000001100

Why using 2 set of ports for host with different speed flagged 16Gb and 32Gb?
It's a best practice preventing SVC ports to negotiate between different speeds on hosts. Dedicated ports for high speed traffic. But on SAN switches leave the auto-negotiation so both can do 32Gb.

SVC port connexion to SAN SW

https://www.ibm.com/support/pages/troubleshooting-svcstorwize-npiv-connectivity

Nowadays (2024), storage using NVMe are not supported, only SCSI over FC. Hosts are supported with NVMe over FC, SCSI over FC, … network storage protocols

For storage IBM change the layer at storage array to storage

V7000:superuser> chsystem -layer storage

• Zone the FC SCSI NPIV (vWWPN) port from storage to SVC physical port (pWWPN)
• For node inter-connection use also pWWPN only.
• For hosts, use vWWPN with SCSI or NVMe protocols.

On SAN switch, for each storage ports, increase the buffercredit to 40 for 16Gb or 32Gb

sansw01:admin> portcfgfportbuffers --enable 0 40

Before configuring all SVC nodes, wait:

• Configure the first node as a cluster node
• Start the other nodes
• Do the private zoning
• All other nodes started 'll be candidates (if they are still configured, go to the GUI and do a remove node)
• Add the candidates nodes to the cluster
• configure ALL service IP (on each node)
• Download and install the IP quorum (check if it's active)
• Create the zoning for the external storage (controllers)
• Change the external storage layer

Now you are ready to configure the Enhanced Stretch Cluster

You can use either the GUI or the command line

3 sites are available by default (lssite), site 3 can't be set as it's assigned to IPquorum

• chnode -site site_id node node_id
• chcontroller –site site_id controller_id
• chost -site site_id host_name
• chsystem -topology stretched

Now you can check the result

SVC:superuser> lssystem | grep topology