Hi oVirt!
I wanted to take a moment to update you on a new storage verb we have
in vdsm called SDM.copy_data. The purpose of this verb is to allow
copying of data between various endpoints* on hosts that are not
necessarily the SPM. This will allow us in the future to spread the
load created by this data-intensive operation across multiple hosts
while providing a better user experience than the current SPM-driven
flow can.
Current status (Sprint 1):
- Basic SDM.copy_data is merged to vdsm
- We still use the SPM host for creating the destination disk and to
serially copy all volumes.
- The engine Move Disk flow is being adapted to use the new verb.
Patches should be merged in the next day or two.
https://gerrit.ovirt.org/#/c/61087/
- New code paths must be activated by setting a config variable:
"update vdc_options set option_value = true \
where option_name = 'DataOperationsByHSM';"
- Currently positive flows are implemented
Next steps:
- Copy progress reporting in UI
- Support negative flows (eg. lost contact with host)
- Use this verb for live storage migration flows
- Vdsm-side locking
- Select a non-SPM host (when available) for copying
Farther out:
- Support for copy in parallel
- Implement other data path verbs (eg. wipe_volume, sparsify_volume)
--
Adam Litke