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https://issues.apache.org/jira/browse/CLOUDSTACK-10310?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16392926#comment-16392926
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ASF GitHub Bot commented on CLOUDSTACK-10310:
---------------------------------------------

wido commented on issue #2472: CLOUDSTACK-10310 Fix KVM reboot on storage issue
URL: https://github.com/apache/cloudstack/pull/2472#issuecomment-371826140
 
 
   Can VM HA handle such a failure? Let's say you have two NFS mounts on that 
host and once fails. You only stop the Agent, but other VMs keep running.
   
   Afaik that can still cause a corruption where a VM is spawned twice in a 
cluster because the other host can't know if that VM is still running or not.
   
   Our investigators aren't that smart. They rely on ICMP and such which might 
be blocked.

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> KVM hosts reboot if there is a short transient storage error
> ------------------------------------------------------------
>
>                 Key: CLOUDSTACK-10310
>                 URL: https://issues.apache.org/jira/browse/CLOUDSTACK-10310
>             Project: CloudStack
>          Issue Type: Improvement
>      Security Level: Public(Anyone can view this level - this is the 
> default.) 
>          Components: KVM
>    Affects Versions: 4.9.0, 4.10.0.0
>            Reporter: Sean Lair
>            Priority: Major
>
> If the KVM heartbeat file can't be written to, the host is rebooted, and thus 
> taking down all VMs running on it.  The code does try 5x times before the 
> reboot, but the there is not a delay between the retires, so they are 5 
> simultaneous retries, which doesn't help.  Standard SAN storage HA operations 
> or quick network blip could cause this reboot to occur.
> Some discussions on the dev mailing list revealed that some people are just 
> commenting out the reboot line in their version of the CloudStack source.
> A better option (and a new PR is being issued) would be have it sleep between 
> tries so it isn't 5x almost simultaneous tries.  Plus, instead of rebooting, 
> the cloudstack-agent could just be stopped on the host instead.  This will 
> cause alerts to be issued and if the host is disconnected long-enough, 
> depending on the HA code in use, VM HA could handle the host failure.
> The built-in reboot of the host seemed drastic



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