Suresh Kumar Anaparti created CLOUDSTACK-9733:
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Summary: Concurrent volume snapshots of a VM are not allowed and
are not limited per host as per the global configuration parameter
"concurrent.snapshots.threshold.perhost".
Key: CLOUDSTACK-9733
URL: https://issues.apache.org/jira/browse/CLOUDSTACK-9733
Project: CloudStack
Issue Type: Bug
Security Level: Public (Anyone can view this level - this is the default.)
Components: Snapshot, Volumes
Reporter: Suresh Kumar Anaparti
Assignee: Suresh Kumar Anaparti
Fix For: 4.10.0.0
Before the VM job framework changes (CLOUDSTACK-669), Concurrent volume (both
root and data) snapshots were allowed per host based on the value of global
config "concurrent.snapshots.threshold.perhost". The volumes could belong to
the same VM or spread across multiple VMs on a given host. The synchronisation
was done based on the host (Id).
As part of the VM job framework changes (CLOUDSTACK-669) in CloudStack 4.4.0, a
separate job queue was introduced for individual VMs with a concurrency level
of 1 (i.e. all operations to a given VM are serialized). Volume snapshot was
also considered as a VM operation as part of these changes and goes through
the VM job queue. These changes made the config
"concurrent.snapshots.threshold.perhost" obsolete (it was also no longer
getting honoured, since there is no single point of enforcement).
Only one volume snapshot of a VM is allowed at any given point of time as the
sync object is the VM (id). So concurrent volume snapshots of a VM are not
allowed and are not limited per host as per the global configuration parameter
"concurrent.snapshots.threshold.perhost".
This functionality needs to be re-introduced to execute more than 1 snapshot of
a VM at a time (when the underlying hypervisor supports) and snapshots should
be limited per host based on the value of
"concurrent.snapshots.threshold.perhost"at the cluster level (for more
flexibility).
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