VMware snapshots not deleted

Last Updated: Apr 08, 2015 11:55AM CEST
Background:
 
All calls to the VMware API (that includes calls to create and delete the snapshot(s)) are done using the SOAP interface to the API.
At backup start, a SOAP session is initiated by connecting and authenticating to the VMware host.
The log shows this as example:
 
2014-09-21 12:00:10.399+02:00 <INFO>      [3740] Connected to vSphere host '192.168.153.35'
This session is then used throughout the complete backup.
There is a timeout for this one session.
The timeout can be defined here http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=2040626
 
Vmware.exe refreshes this session in a 10 minute interval in a separate thread.
 
Possible Problem:
 
In the vmware.exe backup log you may see, that the execution backup calls takes very long, for instance opening the disk, as example:
 
2014-09-21 12:10:22.314+02:00 <INFO>      [3740] Storing virtual disk: tvw-ts1n-000004.vmdk

2014-09-21 12:28:39.919+02:00 <INFO>      [3740] Opened disk 'tvw-ts1n-000004.vmdk' with transport mode 'nbd'
 
Here the open takes 18 minutes. Usually it takes seconds.
It might be the case that backup calls tot e API take so long that the refresh will not take place anymore and the session timeout hits the session.
As a consequence, the session will be closed.
 
You may see this in the log, when the session was closed and the refresh is unsuccessful:
 
2014-09-22 03:14:55.488+02:00 <WARNING>   [3740] SessionRefresher::refresh failed
Aconsequence of the terminated SOAP session ist hat the call to delete the snapshot will never be transmitted to  the VMWare host:
 

2014-09-22 08:23:35.137+02:00 <INFO>      [3740] Removing snapshot '8-snapshot-197' (consolidate: true)
2014-09-22 08:23:50.432+02:00 <ERROR>     [3740] VTools::removeSnapshot@vm.cpp(1353): SOAP error (SOAP 1.1 fault: "":ServerFaultCode[no subcode]
"The session is not authenticated."
Detail:
)
2014-09-22 08:23:57.968+02:00 <WARNING>   [3740] Failed to remove snapshot: A called function returned with an error (VTools::removeSnapshot)
2014-09-22 08:24:01.122+02:00 <ERROR>     [3740] visdk::ServerContext::logout@visdk.cpp(32): SOAP error (SOAP 1.1 fault: "":ServerFaultCode[no subcode]
"The session is not authenticated."
Detail:
)

Solution:

Enlarge the session timeout to 90 minutes using the link given on top of this mail.
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