Round Robin

Has your storage administrator ever contacted you saying only one path is being used by your ESXi environment?  He may have noticed this by looking at the SAN's performance and the total throughput of each path.

 






In this case, all activity is through one of the paths while the other paths are basically idle.

Setting a single LUN in vSphere is easy

1. Select the host - Configuration tab - storage
2. Right click on a datastore - select properties - Manage Paths
3. On Path Selection, ensure it is set to Round Robin

When building an ESXi host, you can run this command via SSH so that Round Robin is set by default:

• esxcli nmp satp setdefaultpsp --satp VMW_SATP_ALUA --psp VMW_PSP_RR

Note:  Make sure you have two dashes for each

If you have multiple ESXi hosts with multiple LUNS, setting each path manually can be time consuming.  In this case, you can use powershell.  This command will look at all LUNS and set the path policy to roundrobin if it's not already set:

• Get-ScsiLun -VmHost <ESXi Host Name> -LunType disk | Where { $_.MultipathPolicy -notlike “roundrobin“}  | Set-ScsiLun -MultipathPolicy “roundrobin"

You can then run this command against all your hosts.

Once everything is set to Round Robin, you and your storage administrator will be much happier as throughput will be spread across all paths.