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Posted to issues@cloudstack.apache.org by "Venkata Siva Vijayendra Bhamidipati (JIRA)" <ji...@apache.org> on 2013/06/19 01:34:20 UTC
[jira] [Commented] (CLOUDSTACK-1352) KVM 6.3 snapshot - when
snapshot of ROOT volume is being created, snapshot of data volume remains
in Creating state
[ https://issues.apache.org/jira/browse/CLOUDSTACK-1352?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13687376#comment-13687376 ]
Venkata Siva Vijayendra Bhamidipati commented on CLOUDSTACK-1352:
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Inability to take snapshots is critical, but why is the inability to take snapshots simultaneously on the same VM critical, especially when the code explicitly disallows it by design?
I see that if the hypervisor is KVM or ESX, a new snapshot operation is not allowed when a snapshot operation on a volume of a VM is already in progress. I am not sure what necessitates putting in this restriction. Some reasons I can think of are that allowing this creates some problems either with snapshot performance because the hypervisor queues the requests up anyway, or runs into hangs, or issues arise with volume integrity because the hypervisor doesn't support it, or the hypervisor outright errors out this kind of simultaneous operation issued through a VM reference.
This restriction was placed long ago in Sep 2011, quite old considering even pre-ASF cloudstack timing, and well before ASF cloudplatform was conceived. It was put it in as part of commit # 2a6de104e21f99dd2a252e94893c364825b68c5d for bug 11531 on bugs.cloud.com (I'm not able to view the bug though). The commit is viewable on the pre-ASF master branch. The change went into SnapshotManagerImpl.java. The code is now in AncientSnapshotStrategy.java. Earlier, this restriction was placed only on VWMare, but now it's for both VMWare and KVM.
Requesting Kelven to put in his comments regarding the rationale of putting in this restriction.
Unless Kelven thinks otherwise, this bug should be closed as by design.
> KVM 6.3 snapshot - when snapshot of ROOT volume is being created, snapshot of data volume remains in Creating state
> -------------------------------------------------------------------------------------------------------------------
>
> Key: CLOUDSTACK-1352
> URL: https://issues.apache.org/jira/browse/CLOUDSTACK-1352
> Project: CloudStack
> Issue Type: Bug
> Security Level: Public(Anyone can view this level - this is the default.)
> Components: Management Server, Storage Controller
> Affects Versions: 4.1.0, 4.2.0
> Environment: MS rhel 6.3 latest build 2/20/2013
> host rhel 6.3 KVM
> Reporter: angeline shen
> Assignee: Venkata Siva Vijayendra Bhamidipati
> Fix For: 4.2.0
>
>
> MS rhel 6.3 latest build 2/20/2013
> host rhel 6.3 KVM latest build 2/20/2013
> 1. advance zone. VPC : VPC network: create VMs
> 2. while snapshot of ROOT volume is being taken, take snapshot of DATA volume
> Result: Error dialog:
> There is other active snapshot tasks on the instance to which the volume is attached, please try again later
> snapshot of data volume remains in Creating state but is deletable.
> This behavior is different than Cloudplatform where snapshot of ROOT volume and DATA volume can be
> taken simultaneously.
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