Nova retains the 'delta' file for the entire snapshot upload time

Bug #1881727 reported by Elancheran S on 2020-06-02
6
This bug affects 1 person
Affects Status Importance Assigned to Milestone
OpenStack Compute (nova)
Undecided
Elancheran S

Bug Description

When the live snapshot happens it setups a 100% copy of the original file using libvirt/qemu to sync the disk to it using "Shallow" mode (this is the .delta file). From that .delta file it extracts the image and uploads it. The delta file remains till the upload completes which results in 3x space required for each snapshots.

To fix this issue, the .delta file can be removed once the image is extracted from the .delta file https://github.com/openstack/nova/blob/stable/pike/nova/virt/libvirt/driver.py#L2007-L2008

Elancheran S (tsecheran) wrote :

When concurrent snapshots happening in a multiple VM's on a hypervisor leads disk space running out due to the 3x space required.

By providing this fix i.e. deleting the '.delta' file would reduce the space requirement for the concurrent snapshots of multiple VMs in a single hypervisor.

Fix proposed to branch: master
Review: https://review.opendev.org/734421

Changed in nova:
assignee: nobody → Elancheran S (tsecheran)
status: New → In Progress
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