To boot vsphere 7.0u3 or 6.7u3 from ARC-1203 raid volume, you have to install the system to raid volume. But in vsphere 7.0u3 or 6.7u3 default does not have build-in areca raid driver. So you cannot install vsphere to ARC-1203 raid volume. In order to install vsphere to ARC-1203 raid volume, you need to build a vsphere  customized ISO file with build-in areca raid driver.

To build a ESXi 7.0 U3 custom iso with arcmsr driver component

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On Windows, run the Microsoft PowerShell.

Add-EsxSoftwareDepot -DepotUrl D:\Areca\VMware-ESXi-7.0U3-18644231-depot.zip

Add-EsxSoftwareDepot -DepotUrl D:\Areca\VMW-esx-7.0.0-arcraid-2.00.00.06-1OEM.650.0.0.4598673.zip

Get-ESXImageProfile

New-EsxImageProfile -CloneProfile ESXi-7.0.3-18644231-standard -Name ESXi-7.0.3-18644231-arcmsrn

Type arc for required verdor:

Add-EsxSoftwarePackage -ImageProfile ESXi-7.0.3-18644231-arcmsrn -SoftwarePackage arcmsrn

Export-EsxImageProfile -ImageProfile ESXi-7.0.3-18644231-arcmsrn -ExportToIso -FilePath D:\Areca\ESXi-7.0.3-18644231-arcmsrn-2000006.iso