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On the booted machine the useful qemu and xen logs will be located under /var/log/xen/*
UEFI/BIOS
UEFI firmware on AVA does not deal well with stale boot entries in the EFI boot manager when such boot entry may not be associated with any disk or partition physically present in the machine. In such case the entry cannot be deleted or updated and, for instance, ubuntu installer fails to finish installation when it cannot add a boot entry due to name duplication. Such situation was observed in practice and probably happened after disk with installed OS was physically removed from the system.
Hence, before removing an NVMe disk from AVA machine it makes sense to delete any EFI boot that can be associated with a disk to be removed.
If such thing happens, the way to restore out of it is to create an empty/fake required UEFI partition and change its UUID usingfdiskto match the entry in EFI boot manager. Afterwards the entry in EFI boot manager becomes valid and can be successfully deleted.UEFI/BIOS freezes or hangs sometimes. It may be related to some weird USB devices attached to the machine when booting into UEFI/BIOS interface.
PCIe
PCIe AER events flood
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