For storage systems with drives that use inline data compression technology, the  Compression Savings does not include the capacity savings that are achieved at the drive  level. Drive level compression occurs after striping across MDisk and the RAID distribution on  the disks/FCM level. There is no information available about which volume a block of data  belongs to that was just compressed, so the information about compression within the drives  is only available at the array level The following formula is used to calculate the amount of storage space that is saved:  (written space • compressed size) The following formula is used to calculate the percentage of capacity that is saved: ((written space • compressed size) ÷ written space) × 100) For example, the written space, which is the amount of data that is written to the volumes  before compression, is 40 GiB. The compressed size, which reflects the size of compressed  data that is written to disk, is just 10 GiB. Therefore, the compression savings percentage  across all compressed volumes is 75%. The estimated amount and percentage of capacity that is saved by using data deduplication,  across all data reduction pools on the storage system. The percentage is calculated across  all deduplicated volumes in the pools and does not include the capacity of volumes that are  not deduplicated. The following formula is used to calculate the amount of storage space that is saved:  (written space • deduplicated size) The following formula is used to calculate the percentage of capacity that is saved: ((written space • deduplicated size) ÷ written space) × 100 For example, the written space, which is the amount of data that is written to the volumes  before deduplication, is 40 GiB. The deduplicated size, which reflects the size of deduplicated  data that is written to disk, is just 10 GB. Therefore, data deduplication reduced the size of the  data that is written by 75%. The percentage of physical capacity in the pools that is allocated to the regular volumes, the  thin-provisioned volumes, and the volumes in child pools. Check the value for physical  allocation to see: GLYPH<SM590000> Whether the physical capacity of the pools is fully allocated. That is, the value for physical  allocation is 100%. GLYPH<SM590000> Whether you have sufficient capacity to provision new volumes with storage. GLYPH<SM590000> Whether you have sufficient capacity to allocate to the compressed and thin-provisioned  volumes. Physical Allocation (%) Deduplication Savings (%) 368  IBM System Storage SAN Volume Controller, IBM Storwize V7000, and IBM FlashSystem 7200 Best 