Which compute resource is this?

This is still present in libvirt resource.

Same thing for oVirt (and probably others) and not only compute profiles but also in host form. The reason is probably the fact that we don't have normal model attribute for that but we serialize volume_attributes as a hash. We should create a non-persistent model for volume and each compute resource should provide mapping methods.

I checked with RHEV and can confirm this is indeed reproducible on Sat 6.9.
I can fill whatever value and it's accepted. If it's just a string of letters, it's then shown in WebUI as 0, if it's a string starting with number, that number is shown in WebUI. However, using Hammer, I can see the value is saved as I entered it, e.g.:

# hammer compute-profile info --id 4
Id:                 4
Name:               testcp
Created at:         2021/04/30 13:41:33
Updated at:         2021/04/30 13:41:33
Compute attributes: 
 1) Id:               1
    Name:             1 Cores and 1 GB memory
    Compute Resource: testrhev
    VM attributes:    {"cluster"=>"<uuid>", "template"=>"", "instance_type"=>"", "cores"=>"1", "sockets"=>"1", "memory"=>"1073741824", "ha"=>"0", "display"=>{"type"=>"vnc", "keyboard_layout"=>"en-us"}, "volumes_attributes"=>{"0"=>{"size_gb"=>"5", "storage_domain"=>"<uuid>", "id"=>"", "preallocate"=>"0", "wipe_after_delete"=>"0", "interface"=>"virtio_scsi"}, "1"=>{"size_gb"=>"0", "storage_domain"=>"<uuid>", "id"=>"", "preallocate"=>"0", "wipe_after_delete"=>"0", "interface"=>"virtio_scsi"}, "<id>"=>{"size_gb"=>"a 4 f", "storage_domain"=>"<uuid>", "id"=>"", "preallocate"=>"0", "wipe_after_delete"=>"0", "interface"=>"virtio_scsi"}, "<id>"=>{"size_gb"=>"4 h", "storage_domain"=>"<uuid>, "id"=>"", "preallocate"=>"0", "wipe_after_delete"=>"0", "interface"=>"virtio_scsi"}}}