[Discuss] Virt-Manager

[epp at sillydog.org (Edward)]

When I try to do this again, this is the text in the virt-manager GUI 
that comes up as soon as I select the icon to create a new virtual machine:

"Warning: KVM is not available. This may mean the KVM package is not 
installed, or the KVM kernel modules are not loaded. Your virtual 
machine may perform poorly."

FWIW, when I did this for the second time last night, it took an hour 
and a half just to install the image (since deleted).

Don't know if the info below will help:

Just now, running ->???? ~$ lspci | grep -i virtio? had no results

/var/log/dmesg no such file or directory

$ sudo dmidecode -s system-manufacturer
Hewlett-Packard

$ sudo dmidecode -s system-product-name
CQ5826


On 10/20/21 4:25 PM, markw at mohawksoft.com wrote:
> Let me back up.
>
> QEMU is the actual emulation software. KVM is a management layer on top of
> that. lib-virt AFAIK work on top of KVM. The virt-manager package sits on
> top of that.
>
> Couple things. "Paravirtualization" is what you really want. You want
> x86[_64] code running on x86[_86] hardware. QEMU will use the
> virtualization and isolation features of the kernel to run the software
> "as is" and trap privileged instructions. You can get "near native" speed.
>
> You also want to use the VirtIO drivers from within the VM
>
> [16:08:36] dut:~ # lspci | grep -i virtio
> 00:03.0 Ethernet controller: Red Hat, Inc. Virtio network device
> 00:06.0 Communication controller: Red Hat, Inc. Virtio console
> 00:07.0 SCSI storage controller: Red Hat, Inc. Virtio block device
> 00:08.0 Unclassified device [00ff]: Red Hat, Inc. Virtio memory balloon
> 00:0b.0 SCSI storage controller: Red Hat, Inc. Virtio block device
> 00:0c.0 SCSI storage controller: Red Hat, Inc. Virtio block device
> 00:0d.0 SCSI storage controller: Red Hat, Inc. Virtio block device
>
> [16:18:04] dut:~ # grep Hypervisor /var/log/dmesg
> [    0.000000] Hypervisor detected: KVM
>
> [16:20:12] dut:~ # dmidecode -s system-manufacturer
> QEMU
> [16:20:27] dut:~ # dmidecode -s system-product-name
> Standard PC (i440FX + PIIX, 1996)
>
> This means that I am not emulating a controller. I/O to the network or
> disk directly interfaces to the hypervisor's system without emulating
> something stupid like emulex, intel, or etc.
>
> The qcow2 is a copy-on-write (cow) format. Every write to the qcow2 file
> is multiplied. If you use a raw file, you lose some of the flexibility of
> the qcow2 format, but speed is improved.
>
> You can shut down the VM and use "qemu-image convert" to go from qcow2 to
> raw.
>
> You can edit the vm definition using virt-manager, edit the disk, and
> click the xml tab, change "type" from "qcow2" to "raw" and update the file
> name.
>
>> Virt-manager created it as a .qcrow2 by default, did not know what that
>> was. There was also an indication that 'the KVM package' was not
>> installed and as a result, it would run slowly. I would have expected
>> the installation of virt-manager to also pull in all required
>> dependencies. Debian does not provide a package named 'kvm' and
>> searching using that string under Description & Name with Synaptic,
>> found no such packages that looked like it would install KVM.
>>
>> I believe the file system it is using, is ext4.
>>
>>
>> On 10/20/21 3:00 PM, markw at mohawksoft.com wrote:
>>> I use KVM all the time and manage it with virt-manager.
>>>
>>> (1) Make sure that network and disk use VirtIO para-virtual driver, do
>>> not
>>> emulate physical devices.
>>>
>>> (2) Don't use qcow2, its really slow. Pre-allocate your boot drive:
>>>
>>> touch myboot.raw
>>> truncate -s SIZE myboot.raw
>>>
>>> The above will let you define a large thin-provisioned disk.
>>>
>>> If you have LVM or ZFS you can create a logical volume or zvol, but I
>>> think the thin provisioned "sparse" file may be faster because of the
>>> double caching.
>>>
>>>> On 10/18/21 9:20 PM, Edward wrote:
>>>>> I missed a setting, found it afterwards, it defaults to Virtual
>>>>> Network
>>>>> (NAT) and the box to start it automatically was initially not checked.
>>>>>
>>>>> It's working now.
>>>>>
>>>> And it (take your pick):
>>>>
>>>>     * is slow as molasses
>>>>     * runs at a snail's pace
>>>>
>>>>
>>>> Not even worth using. Gnome Boxes on Fedora 33 ran far better and
>>>> faster
>>>> than Virt Manager does on Debian.
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>