OPERATIONAL DEFECT DATABASE
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Deduplication/Compression ratio can be low when thick objects are being used.
The objects in vSAN are applied policy with 100% Object Space Reservation (OSR).The UI the storage values indicate the deduplication/compression did not occur and we mark the space as used. This is by design. When OSR is 100%, all of the space is reserved for that VM alone and dedupe/compression will not help as other VMs are not allowed to use this space.In many cases the OSR =100 VMDK are overwritten with zero by vmkfstools -w "paht to vmdk" to ensure all the space is consumed and cleared.
These issues has been resolved in 7.0 where the space utilization in OSR=100 is considered as thick. However , if you want space saving on a disk you may need to change the storage policy back to OSR=0 which will free up the unused free space reserved by OSR=100 The deduplication/compression ratio will increase because we drop the reservation, and report on the actual physical (possibly deduped) usage.See here for definition of "Object Space Reservation":https://docs.vmware.com/en/VMware-vSphere/6.7/com.vmware.vsphere.virtualsan.doc/GUID-08911FD3-2462-4C1C-AE81-0D4DBC8F7990.htmlObject Space Reservation is changed in the assigned Policy by clicking "Edit":HTML Client:https://docs.vmware.com/en/VMware-vSphere/6.7/com.vmware.vsphere.virtualsan.doc/GUID-9A3650CE-36AA-459F-BC9F-D6D6DAAA9EB9.htmlFlash Client:https://docs.vmware.com/en/VMware-vSphere/6.7/com.vmware.vsphere.virtualsan.doc/GUID-EE705FDA-EE34-481E-A84D-1F900AC25FD1.html(Via clicking "Add rule" Object Space Reservation is being added)
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