[CLOUDSTACK-8939] VM Snapshot size with memory is not correctly calculated in cloud.usage_event (XenServer)

• Type: Bug
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 4.5.2
• Security Level: Public (Anyone can view this level - this is the default.)
• Assignee: Unassigned
• Reporter: subhash yedugundla
• Created: 06/Oct/15 16:06
• Updated: 01/Sep/17 09:01

Description

1. created a VM snapshot with memory on a VM with 512 MB RAM
list all the VBDs for the VM
xe vbd-list vm-name-label=i-2-43-VM empty=false params=vdi-uuid
vdi-uuid ( RO) : fbe638dd-02c5-42f5-96b2-7b3d73e68658
Verify the size of the snapshot disk and its parent (I understand from the code we only check one parent in the chain)

1. xe vdi-list params=physical-utilisation,sm-config,is-a-snapshot uuid=fbe638dd-02c5-42f5-96b2-7b3d73e68658
   is-a-snapshot ( RO) : false
   physical-utilisation ( RO): 38124032 <-------------
   sm-config (MRO): host_OpaqueRef:52c1ec01-cef6-d4fd-7d81-68795a853ee0: RW; vhd-parent: 993e3859-8be9-414c-819b-61095ab2eff1
   parent:
2. xe vdi-list params=physical-utilisation,sm-config,is-a-snapshot uuid=993e3859-8be9-414c-819b-61095ab2eff1
   is-a-snapshot ( RO) : false
   physical-utilisation ( RO): 119816704 <-------------
   sm-config (MRO): vhd-blocks: eJxrYAAB0QcMWAELduFBDwSgNAsaHxcQARGMNHMOQfsJARFGRgkGRkWgOxmxGiWCwz5c9qLLU+o+YoGooIBUp6CgIJ2sIxnQKxzoZQ8M0Dof09s/1AMALcYD3A==; vhd-parent: 4b7ee66c-de53-47bb-b3d5-306d40a0ea08
   At this stage, not counting the "suspend VDI", the size looks as follows:
   38124032 + 119816704 = 157940736 = 150.6 MB
   Now, let's calulate the "suspend VDI" size and add it to the above value:
   Note my test VM has 512 MB of RAM
3. xe vdi-list name-label=Suspend\ image params=all

uuid ( RO) : e2ae7a47-c410-479b-9e2b-5f05c01f1b4f
name-label ( RW): Suspend image
name-description ( RW): Suspend image
is-a-snapshot ( RO): true
physical-utilisation ( RO): 6144 <---------------------------------------
sm-config (MRO): vhd-parent: c286583b-dd47-4a21-a5fe-ba2f671f1163
Looking at the parent

1. xe vdi-list uuid=c286583b-dd47-4a21-a5fe-ba2f671f1163 params=all

uuid ( RO) : c286583b-dd47-4a21-a5fe-ba2f671f1163
name-label ( RW): base copy
is-a-snapshot ( RO): false
virtual-size ( RO): 782237696
physical-utilisation ( RO): 252154368 <---------------------------------------
sm-config (MRO): vhd-blocks: eJz7/x8ZNDA0MEDAASiNyucAAHMeEPs=

So the "suspend VDI" + its parent has "physical utilisation" of 6144 + 252154368 = 252160512 = 17.55 MB
Now, if we add it to the previously calculated disk sizes, we'll get:
xapi (phys util): 157940736 (non-memory snap disks)+ 252160512 (memory snap disks) = 410101248 = 391.1 MB
Let's verify the size in cloud.usage_event now:
select * from cloud.usage_event where resource_name like "i-2-43-VM%" \G

id: 528
type: VMSNAPSHOT.CREATE
account_id: 2
created: 2015-04-14 11:48:56
zone_id: 1
resource_id: 43
resource_name: i-2-43-VM_VS_20150414114830
offering_id: NULL
template_id: 64
size: 119863296 <-------------
resource_type: NULL
processed: 0
virtual_size: NULL
1 row in set (0.01 sec)
Overall, the snapshot size in cloud.usage_event != size calculated from xapi objects based on the code
xapi (phys util): 157940736 (non-memory snap disks)+ 252160512 (memory snap disks) = 410101248 = 391.1 MB
but:
usage_event: 119863296 = 114.3 MB

Issue Links

• links to: GitHub Pull Request #914