Boot disk is ignored for ESXi7.x (also storage layout has changed)

[Tom Kivlin]

I've found that when the 'vmfs6' storage layout is applied, the 'boot_disk' is not always used to load the image onto (I've only noticed recently when deploying ESXi7). For example I have created a HW RAID volume which shows up as sdh, and have selected that as the boot disk and then applied the VMFS6 storage layout. But when I deploy esxi7.0 to the server, it loads the image onto sdb (the first disk in the list).

I've noticed the following in the logs, which suggests the choice of boot disk is being ignored because multiple entries are supplied?

block.lookup_disk() returning path /dev/sdh
'custom' mode but multiple devices given. using first found
mode is 'custom'. multiple devices given. using '/dev/sda' (first available)
installing in 'custom' mode to 'sda'

Not sure if it's related, but I noticed the partitions that the VMFS6 layout applies don't match those used by ESXi. Described in detail here: https://blogs.vmware.com/vsphere/2020/05/vsphere-7-esxi-system-storage-changes.html

MAAS version: 2.9.2 (9165-g.c3e7848d1)

The impact of this is that we can use MAAS to configure the hardware, but currently can't use it to deploy ESXi7.0 reliably.