On 10/20/2014 12:50 AM, simonjin wrote:

Hi all,

I'm presenting here my proposal for the feature "Guest migration" which
is expected to be implemented for Kimchi 1.4.
Description
Migrate guest vm within peer/host discovered by Kimchi peers using openSLP.
In the first stage 1, only do migration will be supported,
in stage2, migrateCancel and migrateMonitor will be supported.

Migration Mode:
1. Support libvirt tunnelled transport managed by direct migration.
2. Only support Live migration mode.
3. Only support migration over TCP

Migration Capability Check
- Source libvirtd/client should be able to connect destination libvirtd.
- CPU architectures compare(X86 vs PPC).
- No PCI device passthrough.
- In a shared storage pool and the pool can be access/write by destination.

REST API
Only one new REST command will be added in stage 1.
Syntax
POST /vms/<vm-name>/migrate

You will have a data object informing the destination host

POST /vms/<vm-name>/migrate {host: ...}

Parameters:

in config.py.in:

        ('migration_destination_timeout', '21600',
            'Maximum time the destination waits for the migration to finish.
           21600 should be enough since all the peers will be in the same LAN'),

        ('migration_max_bandwidth', 'unlimited',
              'default in libvirt is unlimited'),

        ('migration_downtime', '500',
            'Maxmium allowed downtime for live migration in milliseconds '
            '(anything below 100ms is ignored) if you do not care about '
            'liveness of migration, set to a very high value, such as '
            '600000.'),

I don't think we need to allow user edits those values so there is no need to add them to config.py.in

Return:
An asynchronous Task with "target_uri" containing "/vms/<new-vm-name>".
As expected with any Task, the cloning process can be tracked by
checking the corresponding task's status.

Do_migration step:
- migration source check .

What kind of verification will be done?
Storage pool and network? Guest permission settings?

- connect migration destination, guest vm config/params transfer and setup.

How will it be done?
From libvirt doc, I can see different types of migration, which one is the best solution for Kimchi?

For reference: http://libvirt.org/migration.html

- migration source prepare.
- do actually migration.

Does libvirt python API have native support for that?

- recover if failed.

Probably, on fail, some leftovers will be on destination server. How will you do the clean up?
Will it be a communication between the Kimchi servers? What about if the destination server does not have a Kimchi setup?

- do finish if migration successful.

Comments are welcome!
-- 
Yun Tong Jin, Simon
Linux Technology Center, Open Virtualization project
IBM Systems & Technology Group
jinyt@cn.ibm.com, Phone: 824549654 