[libvirt] A question about booting from the snapshot image by specifying snapshot id in Libvirt

[harryxiyou]

Hi all,

I test libvirt boots QEMU VM from Sheepdog snapshot image by specify
snapshot id like following.

1, $ collie vdi list
  Name        Id    Size    Used  Shared    Creation time   VDI id  Copies  Tag
  Alice        1   10 GB  1.3 GB  0.0 MB 2013-02-01 18:59   15d167
2
s testvdi      1   20 MB   20 MB  0.0 MB 2013-02-02 11:45   f348ba
2          name
s testvdi      2   20 MB  0.0 MB   20 MB 2013-02-03 17:56   f348bb
2
  testvdi      3   20 MB   12 MB  8.0 MB 2013-02-03 17:58   f348bc     2

2, $ cat > sheepdog_vm1.xml
<domain type='qemu'>
<name>testvm</name>
<memory>1048576</memory>
<os>
<type arch='x86_64'>hvm</type>
</os>
<devices>
<disk type='network'>
<source protocol="sheepdog" name="testvdi:1"/>
<target dev='hda' bus='ide'/>
</disk>
<graphics type='vnc' port='-1' autoport='yes'/>
</devices>
</domain>

3, $ virsh create sheepdog_vm1.xml
domain testvm is created ( from sheepdog_vm1.xml）

4, $ virsh destroy testvm
domain testvm is deleted

5, $ collie vdi list
  Name        Id    Size    Used  Shared    Creation time   VDI id  Copies  Tag
  Alice        1   10 GB  1.3 GB  0.0 MB 2013-02-01 18:59   15d167
2
s testvdi      1   20 MB   20 MB  0.0 MB 2013-02-02 11:45   f348ba
2          name
s testvdi      2   20 MB  0.0 MB   20 MB 2013-02-03 17:56   f348bb
2
s testvdi      3   20 MB   12 MB  8.0 MB 2013-02-03 17:58   f348bc
2
  testvdi      4   20 MB   12 MB  8.0 MB 2013-02-04 13:15   f348bd     2


My question is before i boot VM from sheepdog:testvdi:1, my vdi list like
  Name        Id    Size    Used  Shared    Creation time   VDI id  Copies  Tag
  Alice        1   10 GB  1.3 GB  0.0 MB 2013-02-01 18:59   15d167
2
s testvdi      1   20 MB   20 MB  0.0 MB 2013-02-02 11:45   f348ba
2          name
s testvdi      2   20 MB  0.0 MB   20 MB 2013-02-03 17:56   f348bb
2
  testvdi      3   20 MB   12 MB  8.0 MB 2013-02-03 17:58   f348bc     2

However, after VM is destroied, my vdi list like
  Name        Id    Size    Used  Shared    Creation time   VDI id  Copies  Tag
  Alice        1   10 GB  1.3 GB  0.0 MB 2013-02-01 18:59   15d167
2
s testvdi      1   20 MB   20 MB  0.0 MB 2013-02-02 11:45   f348ba
2          name
s testvdi      2   20 MB  0.0 MB   20 MB 2013-02-03 17:56   f348bb
2
s testvdi      3   20 MB   12 MB  8.0 MB 2013-02-03 17:58   f348bc
2
  testvdi      4   20 MB   12 MB  8.0 MB 2013-02-04 13:15   f348bd     2

There is another snapshot of testvdi created. I am not clear about why another
one is created? I just boot a VM from snapshot testvdi, which id is 1.

Could anyone please give me some suggestions? Thanks in advance ;-)


-- 
Thanks
Harry Wei