[libvirt-users] virDomainBlockInfo for local volume

[Shahar Havivi]

Ping

On Wed, Nov 30, 2016 at 3:13 PM, Shahar Havivi <shavivi at redhat.com> wrote:

> Hi,
>
> I am using virStorageVolGetInfo to get the volume size
> virStorageVol.download to download a
> normal file for VDSM project.
>
> I want to add support for block devices as well, I was able to see the size
> via virDomainBlockInfo and download via virDomain.blockPeek which is works
> fine for both file and block device.
>
> 1. Can I depend on virDomainBlockInfo for non block devices?
> 2. Does the virDomainBlockInfo return the correct physical size for normal
> file?
> 3. Performance wise do we have a difference between virStorageVol.download
> and virDomain.blockPeek?
>
>
> Assuming the VMs are down, this is the code I intend to use for all
> formats:
>
> vm = con.lookupByName(options.vmname)
> info = vm.blockInfo(src)
> physical = info[2]
>
> off = 0
> size = 0
> with open(dest, 'w+') as f:
>     while off < physical:
>         if (physical - off) < bufsize:
>             size = physical - off
>         else:
>             size = bufsize
>         buf = vm.blockPeek(src, off, size)
>         f.write(buf)
>         off += size
>
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