Okay,
here then a post detailing a ROCK running in a Linux KVM VM on a CentOS 7.6 Server.
The VM has 2GB and 2 vCPUs, a SATA disk (using a 20GB qcow3 disk image), because sadly VirtIO disk drivers are not included in the ROCK image, but nicely enough a VirtIO network card worked fine.
ROCK says Roon Database has 91% of 16 GB available with about 11,000 Songs indexed.
Performance is fine, and seems to be the same as on a Roon core running in a Windows 10 VM, and same as a Roon core running natively on the CentOS Server.
Two disadvantages of ROCK seem to be a) doesn’t run extensions b) is fixed to a UTC time zone, causing Squeezeboxen to show UTC time.
-Chris