Recovering from configuration that prevents accurate physical capacity reporting

If the system supports self-compressing drives, certain system configurations make determining accurate usable capacity on the system difficult. If the system contains self-compressed drives and data reduction pools without compressed volumes, the system cannot determine the accurate amount of usable capacity that is used on the system. In this case, overprovisioning and losing access to write operations is possible. If this condition is detected by the system, the Usable Capacity section of the Dashboard page displays a message instead of capacity information. To recover from this condition, you need to ensure that all thin-provisioned volumes and thin-provisioned volumes that are deduplicated are migrated to volumes with compression enabled in the data reduction pools. Alternatively, you can migrate the volumes to standard-provisioned volumes and use the drive compression to save capacity.

You can use volume mirroring to enable compression on existing volumes in data reduction pools. Because data reduction pools also support deduplication, you can add that function to compressed volumes to gain extra capacity savings. After the original volumes are deleted from the data reduction pool, the capacity from those volumes is added to the reclaimable capacity for the system, and the error is removed from the Dashboard. Depending on the amount of reclaimable capacity on the system, the system can take some time to remove the reclaimable capacity from the system. During that process, the usable capacity tends to shrink in size. If you want to use self-compressing drives, convert these volumes to standard-provisioned volumes that can be used in a standard pool that uses self-compressing drives for storage. In the management GUI, you can use the Modify Capacity Savings action to quickly convert the capacity savings method for your volumes. This action creates a mirrored volume of the original, with the new capacity savings method enabled, then automatically deletes the original version from the pool.

If you have data reduction pools that contain volumes without compression on systems that contain self-compressing drives, you need to convert all these volumes to enable compression. Accurate reporting for usable capacity is unavailable for these configurations. To change the capacity savings on volumes in data reduction pools, complete these steps:
  1. In the management GUI, select Volumes > Volumes by Pools. The left navigation displays all the configured pools on the system and expands the data reduction pool that contains the volumes that you want to change the capacity savings method for.
  2. Right-click the volume that you want to convert and select Modify Capacity Savings. Since this process creates volume copies to manage the conversion, ensure that the pool has enough storage to accommodate these volume copies. For example, if you are converting a volume that has 2 GB allocated capacity, ensure that the pool has another 2 GB to accommodate both the original version and the copy during the conversion. After the conversion completes, the original copy is automatically deleted from the pool. You can also convert volumes in standard pools to data reduction pools to use the data reduction features that are available in these pools. For that method, you need to create a new data reduction pool and volume mirroring.
  3. On the Modify Capacity Savings page, select Compression to change the currently configured capacity setting to enable compression. For additional capacity savings, you can also select Deduplicated to remove duplicate data from the pool.
  4. Click Modify. After the original volumes are deleted from the data reduction pool, the capacity from those volumes is added to the reclaimable capacity for the system, and the error is removed from the Dashboard. Depending on the amount of reclaimable capacity on the system, the system can take some time to remove the reclaimable capacity from the system. During that process, the usable capacity tends to shrink in size.