Folks following up on this thread looks like support for XenServer is still not settled.
1. Mice can we make the feature configurable for each hypervisor to enable/disable the feature 2. Test the feature with XenServer thoroughly to check if Volume Snapshot is affected / degraded Thanks Animesh > -----Original Message----- > From: Anthony Xu [mailto:xuefei...@citrix.com] > Sent: Friday, February 01, 2013 5:44 PM > To: 'Mice Xia'; cloudstack-dev@incubator.apache.org; Alex Huang; Mice Xia > Subject: RE: [MERGE] Support VM Snapshot > > I see, snapshot manager detected the change in primary storage, and create > a full snapshot instead, which is supposed to be a delta snapshot. > > It doesn’t break volume snapshot function, but this degrades the volume > snapshot performance. > > > > This is just a simple test, it cannot prove there is no impact to volume > snapshot. > > I’m not sure what will happen if execute these two commands at the same > time, is there any mechanism to sync/serialize these two operation? > > I’m not sure if revert VM has impact to volume snapshot. > > > > For now, it is better to have a global configuration to only choose one. > > later, we may support both of them in one setup. > > > > > > Anthony > > > > > > > From: Mice Xia [mailto:mice_...@tcloudcomputing.com] > Sent: Friday, February 01, 2013 5:30 PM > To: cloudstack-dev@incubator.apache.org; Alex Huang; Mice Xia; Anthony Xu > Subject: 答复: [MERGE] Support VM Snapshot > > > Anthony, > > Thanks for your comments. > > Tested on a datadisk with steps you provide on xenserver, all the files > (test1, > test2, test3) are present, the function is not affected. > But as i have replied, volume snapshot (s2) is not a delta snapshot, it is a > full > one. Users need to be aware of this if they want to use both snapshots > simultaneously. > > Regards > Mice > > > -----Original Message----- > From: Anthony Xu [mailto:xuefei...@citrix.com] > Sent: 2013-2-2 (星期六) 4:05 > To: Alex Huang; Mice Xia; cloudstack-dev@incubator.apache.org > Subject: RE: [MERGE] Support VM Snapshot > > CS uses XenServer delta snapshot, snapshot manager records a VHD chain in > snapshot DB for each volume. VM snapshot creation/revert also operate on > volume snapshot, if snapshot manager doesn't know the VM snapshot , > volume snapshot might be broken. > > > You can try following test, > > 1. create a VM. > 2. create empty file test1 inside this VM. > 3. create a volume snapshot(s1) > 4. create empty file test2 inside this VM 5. create a VM snapshot (vm1) 6. > create empty file test3 inside this VM 7. create a volume snapshot (s2) 8. > create a volume from snapshot (s2) 9. attach this volume to a VM 10. if one > of test1, test2, test3 is missing in this volume, might mean volume snapshot > is broken. > > > It might be difficult to support both VM snapshot and volume snapshot in the > same time for hypervisor which supports delta snapshot. > Maybe we need to provide a zone level configuration for it, only one is > supported in a zone, volume snapshot or vm snapshot. > > > > Anthony > > > > > > > -----Original Message----- > > From: Alex Huang > > Sent: Friday, February 01, 2013 10:54 AM > > To: Mice Xia; cloudstack-dev@incubator.apache.org > > Cc: Anthony Xu > > Subject: RE: [MERGE] Support VM Snapshot > > > > Mice, > > > > Thanks! > > > > Anthony, > > > > Can you comment on whether VM Snapshot breaks volume snapshot? > > > > --Alex > > > > > -----Original Message----- > > > From: Mice Xia [mailto:weiran.x...@gmail.com] > > > Sent: Friday, February 01, 2013 8:53 AM > > > To: cloudstack-dev@incubator.apache.org; Alex Huang > > > Subject: Re: [MERGE] Support VM Snapshot > > > > > > as Alex suggested > > > updated vm-snapshot branch, commit ebca6890fd > > > > > > 1. remove snapshotting/revertting state from VM state machine > > > 2 prevent VM state change if there are active vm snapshot tasks > > > 3 change VMSnapshotService interface, except for ListVMSnapshotCmd, > > > need some time to replace it in QueryService, maybe after merging to > > > master > > > 4 remove unused methods and fix some typos > > > > > > Regards > > > Mice > > > > > > 2013/2/1 Mice Xia <mice_...@tcloudcomputing.com>: > > > > Hi, Alex, > > > > > > > > Thanks for your feedbacks, please see my comments inline. > > > > > > > > - VM states is designed for VM lifecycle. Snapshot is not part of > > VM life > > > cycle so therefore the state should not be there. I think it make > > sense to add > > > attributes to VM that says "Do Not Change State" and who changed > > > the > > VM > > > to that state. Then virtualmachinemanager must obey that until the > > external > > > caller changes the attribute to now you can change state. The would > > make > > > more sense and decouples snapshotting from vm lifecycle management. > > > Snapshotting then has it's own state (which I see it does already). > > If we want > > > to reflect that a vm snapshot is being taken of a VM, that's a > > function of the > > > apiresponse module that gathers up everything about a vm but it > > shouldn't > > > be changed in the vm states. > > > > > > > > [mice] the reason that I added snapshotting/reverting state is > > > > that > > VM > > > could be in suspend/pause state during snapshoting/reverting, which > > is > > > difficult to be categorized into existing states; and during the > > process, VM > > > should not be allowed to take any operations; and by adding new > > states to > > > VM, the implementation seems more 'natural' and only minimum codes > > are > > > changed to virtualmachinemanager. > > > > Of course there are some other ways to prevent operations, such as > > check > > > if associated snapshots are in snapshotting/reverting states either > > in each > > > method (start/stop/migrate/delete...) or hook stateTransitTo(), but > > in this > > > way, it does not reflect VM's real state in hypervisor and more > > existing codes > > > will be touched. > > > > > > > > - Does VM Revert operation work in the following way: Stop VM, > > restore > > > to snapshot, and run VM? Shouldn't this be orchestration inside > > snapshot > > > manager? > > > > > > > > [mice] if a running VM is reverted to a memory enabled snapshot, > > current > > > implementation is running--> reverting-->running > > > > If a stopped VM is reverted to memory disabled snapshot: stopped-- > > > >reverting->stopped > > > > If a running VM is reverted to a memory disabled snapshot: > > > > running- > > -(Stop > > > VM)-->stopped-->reverting--> stopped > > > > If a stopped VM is reverted to a memory enabled snapshot: > > > > stopped-- > > > (Start VM)-->running->reverting-->running > > > > > > > > These logics are implemented in snapshot manager. > > > > > > > > - Does VM snapshot interfere with volume snapshot? Volume > > > > snapshot > > > today makes the assumption that it is the only code that's making > > snapshots > > > and can break if there are additional snapshots in between. This is > > bad > > > design in volume snapshot but unfortunately that's how it's design. > > > > > > > > [mice] about volume snapshot, for xensever, if parent VHD cannot > > > > be > > > found, it will take a full volume snapshot (this indeed break > > > current semantics but it still works) > > > > For vmware, the volume snapshot is always a full one. > > > > > > > > - VMSnapshotService follows the other services in passing the cmds > > to the > > > service. That's really a bad practice that we should stop. Cmds > > > are > > really > > > translations between over-the-wire api and java interface. They > > shouldn't > > > have been passed to down to the java interface. > > > > [ > > > > mice] I'll change it > > > > > > > > A small note: Would it be better to call it VM restore than VM > > revert? > > > Revert really should be RevertTo which I think is in the code but is > > not > > > consistent. Some places it's just REVERT (for example, the event is > > just > > > revert). > > > > > > > > [mice] there is already RESTORE, which is restoring a destroyed VM > > to > > > stopped. RevertTo is fine with me. > > > > > > > > -Mice > > > > > > > > > > > > -----Original Message----- > > > > From: Alex Huang [mailto:alex.hu...@citrix.com] > > > > Sent: Friday, February 01, 2013 9:24 AM > > > > To: CloudStack DeveloperList > > > > Cc: Mice Xia > > > > Subject: RE: [MERGE] Support VM Snapshot > > > > > > > > Hi Mice, > > > > > > > > Sorry it took so long to review this. Wanted to as soon as I saw > > it on the list > > > but was sick and didn't get a chance. In general, I think the code > > is excellent. > > > I'm impressed how much Cloudstack internal code in touch and how > > > comfortable the changes look. Nicely done! > > > > > > > > I have a few comments: > > > > - VM states is designed for VM lifecycle. Snapshot is not part of > > VM life > > > cycle so therefore the state should not be there. I think it make > > sense to add > > > attributes to VM that says "Do Not Change State" and who changed > > > the > > VM > > > to that state. Then virtualmachinemanager must obey that until the > > external > > > caller changes the attribute to now you can change state. The would > > make > > > more sense and decouples snapshotting from vm lifecycle management. > > > Snapshotting then has it's own state (which I see it does already). > > If we want > > > to reflect that a vm snapshot is being taken of a VM, that's a > > function of the > > > apiresponse module that gathers up everything about a vm but it > > shouldn't > > > be changed in the vm states. > > > > - Does VM Revert operation work in the following way: Stop VM, > > restore > > > to snapshot, and run VM? Shouldn't this be orchestration inside > > snapshot > > > manager? > > > > - Does VM snapshot interfere with volume snapshot? Volume > > > > snapshot > > > today makes the assumption that it is the only code that's making > > snapshots > > > and can break if there are additional snapshots in between. This is > > bad > > > design in volume snapshot but unfortunately that's how it's design. > > > > - VMSnapshotService follows the other services in passing the cmds > > to the > > > service. That's really a bad practice that we should stop. Cmds > > > are > > really > > > translations between over-the-wire api and java interface. They > > shouldn't > > > have been passed to down to the java interface. > > > > > > > > A small note: Would it be better to call it VM restore than VM > > revert? > > > Revert really should be RevertTo which I think is in the code but is > > not > > > consistent. Some places it's just REVERT (for example, the event is > > just > > > revert). > > > > > > > > --Alex > > > > > > > >> -----Original Message----- > > > >> From: Chiradeep Vittal > > > >> Sent: Wednesday, January 30, 2013 4:44 PM > > > >> To: CloudStack DeveloperList > > > >> Cc: Alex Huang > > > >> Subject: Re: [MERGE] Support VM Snapshot > > > >> > > > >> Can we get Alex to review this? He is the designer of the state > > machine. > > > >> > > > >> On 1/30/13 5:26 AM, "Murali Reddy" <murali.re...@citrix.com> > wrote: > > > >> > > > >> >On 30/01/13 2:24 PM, "Mice Xia" <mice_...@tcloudcomputing.com> > > > wrote: > > > >> > > > > >> >>Agreed. > > > >> >>Adding VM states are likely to have some side-effects, but for > > > >> >>moveVMToUser case, does it explicitly reject other transient > > states > > > >> >>such as stating/stopping/migrating? > > > >> >> > > > >> >>-Mice > > > >> > > > > >> >No, it just accepts any state other than 'Running' (though it > > should > > > >> >have checked for the valid states in which VM can move to other > > user). > > > >> > > > > >> >I am just saying, there could such VM state based assumptions, > > you > > > >> >might want to check. > > > >> > > > > >
