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https://issues.apache.org/jira/browse/CLOUDSTACK-10241?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16419576#comment-16419576
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ASF subversion and git services commented on CLOUDSTACK-10241:
--------------------------------------------------------------

Commit 060715e9f5f929804b7f515cfba0b4b130581876 in cloudstack's branch 
refs/heads/master from [~rafaelweingartner]
[ https://gitbox.apache.org/repos/asf?p=cloudstack.git;h=060715e ]

[CLOUDSTACK-10241] Duplicated file SRs being created in XenServer pools (#2414)

* [CLOUDSTACK-10241] Duplicated file SRs being created in XenServer pools

Due to a race condition between multiple management servers, in some rare 
cases, CloudStack is creating multiple file SRs to the same secondary folder. 
This causes a problem when introducing the SR to the XenServer pools, as “there 
will be VDIs with duplicated UUIDs“. The VDIs are the same, but they are seen 
in different SRs, and therefore cause an error.

The solution to avoid race conditions between management servers is to use a 
deterministic srUuid for the file SR to be created (we are leaving XenServer 
with the burden of managing race conditions). The UUID is based on the SR file 
path and is generated using  UUID#nameUUIDFromBytes. Therefore, if there is an 
SR with the generated UUID, this means that some other management server has 
just created it. An exception will occur and it will contain a message saying 
'Db_exn.Uniqueness_constraint_violation'. In these unlikely events, we catch 
the exception and use the method retrieveAlreadyConfiguredSrWithoutException to 
get the SR that has already been created for the given mount point.


> Duplicated file SRs being created in XenServer pools
> ----------------------------------------------------
>
>                 Key: CLOUDSTACK-10241
>                 URL: https://issues.apache.org/jira/browse/CLOUDSTACK-10241
>             Project: CloudStack
>          Issue Type: Bug
>      Security Level: Public(Anyone can view this level - this is the 
> default.) 
>            Reporter: Rafael Weingärtner
>            Assignee: Rafael Weingärtner
>            Priority: Major
>
> Due to a race condition between multiple management servers, in some rare 
> cases, CloudStack is creating multiple file SRs to the same secondary folder. 
> This causes a problem when introducing the SR to the XenServer pools, as 
> “there will be VDIs with duplicated UUIDs“. The VDIs are the same, but they 
> are seen in different SRs, and therefore cause an error.



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