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