[one-users] [DEV] Questions about scale-in implementation in OpenNebula

[Paul Grandperrin]

Hi all,

I'm implementing scale-in features in OpenNebula like live memory
growth/shrinking and vcpus hotplugging/hotunplugging.

You can see my git there: http://paulg.fr/gitweb/?p=one.git;a=summary;js=1
My developement branch is feature-scalein. It's still very much a WIP most
of the interesting code is there and basic features are functionnal on Xen
at the moment.
My dev branch is based on one-3.2 but can easily be rebased on master.

Everything is meant to eventualy hit upstream, that why I'd like to get
some advices and feedback from you.

Here are my questions:

1. About VM memory scaling: Currently, AFAIK the vm.memory is used when
deploying a VM to set it's initial memory and then is regularly updated via
hypervisor polling.
    ATM, i'm also using this attribute to change memory size. I think it's
really not the best way thing to do. I'd like to separate theses different
things in separate variables.
    For exemple:
       -memory: the same as of now.
       -memory_target: the target amount of memory when scaling memory.

    I could also use VM history but I'm not very familiar with this class.

2. When scalling the number of VCPUs, should we also scale the VM's cpu
share? If so, how to implement it?

3. In the case of a scalling failure (memory or vcpu), what should we do?
   -Consider the VM failed and not usable anymore? (I think it's way too
strict)
   -Consider the VM still ACTIVE. However, how to inform the user about the
failure (something else than writing in logs).
    And then what should we do?
       -immediatly throw a monitor request to update to the correct value?
       -Consider the worst case: if scaling down the memory => consider the
old value/ if scaling up the memory, consider the new value
       -Other ideas?

Any suggestions about the code structure, writing style, naming
conventions, whatever... are welcome :D

You can also see my TODO list here:
http://paulg.fr/gitweb/?p=one.git;a=blob_plain;f=TODO;h=79c65a4a6eba19095a43191a75fc1e5d58d7e01a;hb=refs/heads/feature-scalein;js=1

What changed:
paulg at debian-pro:~/projects/one$ git diff one-3.2 --stat
 TODO                                      |   12 ++
 include/DispatchManager.h                 |   20 +++
 include/LifeCycleManager.h                |   20 +++-
 include/RequestManagerVirtualMachine.h    |   36 +++++
 include/VirtualMachine.h                  |   43 +++++-
 include/VirtualMachineManager.h           |   50 +++++--
 include/VirtualMachineManagerDriver.h     |   50 +++++--
 install.sh                                |    4 +-
 share/man/onevm.1                         |   60 ++++++++
 src/cli/one_helper.rb                     |    2 +-
 src/cli/one_helper/onevm_helper.rb        |   24 +++
 src/cli/onevm                             |   32 ++++
 src/dm/DispatchManagerActions.cc          |   90 +++++++++++
 src/lcm/LifeCycleActions.cc               |   68 +++++++++-
 src/lcm/LifeCycleManager.cc               |   48 ++++++
 src/lcm/LifeCycleStates.cc                |  123 +++++++++++++++
 src/mad/ruby/VirtualMachineDriver.rb      |   56 +++++--
 src/oca/ruby/OpenNebula/VirtualMachine.rb |   27 +++-
 src/rm/RequestManager.cc                  |    4 +
 src/rm/RequestManagerVirtualMachine.cc    |  105 +++++++++++++-
 src/vm/VirtualMachine.cc                  |    3 +
 src/vmm/VirtualMachineManager.cc          |  231
+++++++++++++++++++++++++++--
 src/vmm/VirtualMachineManagerDriver.cc    |   72 +++++++++-
 src/vmm_mad/dummy/one_vmm_dummy.rb        |    8 +
 src/vmm_mad/exec/one_vmm_exec.rb          |   42 +++++-
 src/vmm_mad/exec/one_vmm_sh               |    2 +-
 src/vmm_mad/remotes/xen/scale_memory      |   26 ++++
 src/vmm_mad/remotes/xen/scale_vcpu        |   26 ++++
 src/vmm_mad/remotes/xen/xenrc             |    3 +-
 29 files changed, 1204 insertions(+), 83 deletions(-)

Thank for your help,

Paul Grandperrin
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