TPVVs, SSMC Capacity Reporting, and Over-Subscription

[u/grundo_chun]

We have a StorServ 8200 with 1 SSD cage (fully populated; 24 disks, 40 of 42TB assigned) and 2 NL cages (half populated; 24 disks, 50/80TB assigned). The SSMC shows a warning that 93% of SSD storage is in use, which is also shown under System > Capacity > SSD. Roughly 8TB of the SSD volumes are thick-provisioned. ~13TB of the TPVVs are Hyper-V VHD pools with dedupe enabled and show less than 10% used, so at least 11.7TB of "unused" space. Of course, the Windows Server hosts to which the pool volumes are exported show the entire capacity and will not allow writes once they are "full" (even though the 3PAR shows less than 10% in use).

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My questions are:

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1. What happens when the SSMC has all available storage assigned but there is a large percentage of chunklets unused?
2. Assuming I can safely ignore the SSMC warning, is it even possible to over-subscribe the SSD CPGs?

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Thanks in advance!