Re: [Qemu-devel] kvm / virsh snapshot management

[Eric Blake]

On 6/10/19 4:27 PM, Gary Dale wrote:

>>
> Trying this against a test VM, I ran into a roadblock. My command line
> and the results are:
> 
> # virsh blockcommit stretch "/home/secure/virtual/stretch.qcow2" --top
> stretchS3 --delete --wait
> error: unsupported flags (0x2) in function qemuDomainBlockCommit
> 
> I get the same thing when the path to the qcow2 file isn't quoted.

That's a libvirt limitation - the --delete flag is documented from the
generic API standpoint, but not (yet) implemented for the qemu driver
within libvirt. For now, you have to omit --delete from your virsh
command line, and then manually 'rm' the unused external file after the
fact.

> 
> I noted in
> https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/6/html/virtualization_administration_guide/sub-sect-domain_commands-using_blockcommit_to_shorten_a_backing_chain
> that the options use a single "-".

Sounds like a bug in that documentation.

> However the results for that were:
> # virsh blockcommit stretch /home/secure/virtual/stretch.qcow2 -top
> stretchS3 -delete -wait
> error: Scaled numeric value '-top' for <--bandwidth> option is malformed
> or out of range
> 
> which looks like virsh doesn't like the single dashes and is trying to
> interpret them as positional options.
> 
> I also did a
> 
> # virsh domblklist stretch
> Target     Source
> ------------------------------------------------
> vda        /home/secure/virtual/stretch.qcow2
> hda        -
> 
> and tried using vda instead of the full path in the blockcommit but got
> the same error.
> 
> Any ideas on what I'm doing wrong?

Do you know for sure whether you have internal or external snapshots?
And at this point, your questions are starting to wander more into
libvirt territory.

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org

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