rocky: ephemeral disk can not be resized

[Jiang]

I installed rocky via rdo. Backend virtualization is qemu-kvm 2.9.0.

I create a cirros vm with flavor: 1 vcpu, 64M ram, 1G disk, 1G ephemeral disk.
I can found ephemeral disk in cirros vm, I can mount ephemeral disk and write datas to it.

But, when I use new flavor（1 vcpu, 64M ram, 1G disk, 2G ephemeral disk） to resize the cirros vm, the ephemeral disk size not changed. I found it still 1G in cirros vm.

[Matt Riedemann (mriedem)]

I believe this is a known limitation that ephemeral (and swap) disks are not resized (nor migrated from host to host) - they are purely ephemeral for the given host they are on. I believe the original 1GB ephemeral block_device_mappings table entry from the initial server create is what is used to create the ephemeral block device on the destination compute host during the resize, and that's why the size doesn't change.