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  • 1.  vSAN OSA increased datastore oversubscription rate after upgrade to 8.03

    Posted Sep 21, 2025 10:14 AM

    Hi,

    did anybody experience a heavy increase of the vSANDatastore oversubscription after upgrade from 7.x to 8.x?

    We have some systems where the rate increases from 0.xx to 5.xx and up to 12.xx. 

    Regards



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  • 2.  RE: vSAN OSA increased datastore oversubscription rate after upgrade to 8.03

    Posted Nov 07, 2025 03:09 AM

    I can't be completely certain, but this KB might be related to the issue.

    https://knowledge.broadcom.com/external/article/397945/vms-are-unreachable-during-upgrade-from.htm

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    Original Message


  • 3.  RE: vSAN OSA increased datastore oversubscription rate after upgrade to 8.03

    Posted Nov 13, 2025 10:47 AM

    @mpac - might you be able to give some insight into what types of data are stored on this cluster?

    e.g. data replicated from somewhere else, large amount of vSAN NFS/SMB file shares, large amount of vSAN iSCSI storage.

    Reason I ask is one of my colleagues mentioned something similar from a case opened with GS and the indication was that for some type(s) of data (cannot recall which off top of my head) had incorrect calculations in vSAN 7.x which was corrected in 8.x (e.g. that 7.x calculation of this was incorrect).

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    Original Message


  • 4.  RE: vSAN OSA increased datastore oversubscription rate after upgrade to 8.03

    Posted Nov 13, 2025 01:33 PM

    Hi,

    the problem is solved by Broadcom support. I had to reset my view to the vSAN datastore. It is not only a files system, it is an object store. The calculation of oversubscription depends not only on the files on the vmfs storage it depends in addition on the objects. If you have a vmdk and you delete it on the vmfs it is possible that it remains as an object. The change from vSphere 7 to 8 is that the calculation of oversubscription includes more object types and all this objects are thin provisioned. 

    The secret is to find these object lists. It is the localcli_vsan-debug-object-list.txt which is created when the esxi host bundle is created. You can look in this and grep the info's you need. We found a lot of vmdk objects which did not exist anymore. They had been created  and deleted by VEEAM surebackup restore tests. 

    I never heard about this file in any documentation, vSAN training or vSAN boot camp. Did anybody else ever analyze this file?

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    Original Message