The Alcadis documentation that you quoted below specifically mentions KVM,
and also does not mention Xen. While Xen is a great technology, depending
on what Alcadis' software is doing you may or may not have issues, and
they may deny support before much investigation based on the hypervisor,
which would probably ruin your day, particularly if you are having a
severe issue in production.

With that written, OVA is an archive of virtualization data, and I think
you can extract it with 'tar' (as it is a TAR file). Since OVA is an
archive, and it appears you have a RAW file within, I would guess you can
use that directly with Xen.

I doubt KVM and Xen can be on the same system, but I have not tried. KVM
is part of the mainline kernel, which means it is available in the default
kernels shipping with SLES 11 (later SPs) and SLES 12. On the other hand,
Xen is part of an alternate kernel, which is why you have boot options for
either the default kernel or the Xen kernel. I doubt the KVM
functionality is in the Xen kernel, but I do not know or have a way to
test right now.

Regarding what to do going forward, Xen has been very good to me, but KVM
is supported by more distros. When SUSE first added support for KVM there
were questions about whether or not Xen would be dropped, but then SLES 12
was released with support for both still, so at the very least Xen will be
around for many more years (SLES 12 support is something like thirteen
years, and we're only a couple of years in). I use KVM on my laptop
(because running the Xen kernel is not an option) and both formats on
various servers.

--
Good luck.

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