After a host writes to a thin provisioned volume, the physical capacity is allocated to the host file system. Unfortunately, if the host deletes the file, only the host file system frees up that space. The physical capacity of the storage system remains unchanged. The storage system does not free up the capacity from the deleted host file; this capacity is commonly referred to as “dead space”. Obviously, this method is not the most effective one for handling back-end block-level storage. Ideally, when a host deletes files, that space should be reclaimed by the host file system and the back-end storage system.
This Technote explains how the IBM XIV Storage System Gen3 with IBM XIV Storage Software V11.2 can now fully use its thin provisioning capability by enabling support for the Windows Server 2012 space reclamation feature.
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