For greatest control and flexibility, you can use the  mkarray  command-line interface (CLI)  command to configure a nondistributed array on your system. However, the suggested  organization for the IBM FlashSystem 9100 is to configure a distributed array (DRAID6). You  can use the  mkdistributedarray  command to do this. Note:  DRAID6 arrays give better performance and rebuild times in the event of a FCM or  NVMe drive failing, because the spare capacity allocated for the rebuild is shared across  all of the drives in the system, and not reserved to one physical drive, as we have in the  traditional RAID arrays. Additionally, MDisks are also created for each external storage-attached LUN assigned to  the IBM FlashSystem 9100 as a managed or as un-managed MDisk for migrating data.  A managed MDisk is an MDisk that is assigned as a member of a storage pool: Information:  For the most up-to-date IBM FlashSystem 9100 configuration limits, go to  the configuration for the IBM FlashSystem 9100 family. Each MDisk is divided into chunks of equal size called  extents . Extents are a unit of mapping  that provides the logical connection between MDisks and volume copies. The extent size is a property of the storage pool and is set when the storage pool is created.  All MDisks in the storage pool have the same extent size, and all volumes that are allocated  from the storage pool have the same extent size. The extent size of a storage pool cannot be  changed. If you want another extent size, the storage pool must be deleted and a new storage  pool configured.  The IBM FlashSystem 9100 supports extent sizes of 16 MB, 32 MB, 64 MB, 128 MB, 256 MB,  512 MB, 1024 MB, 2048 MB, 4096 MB, and 8192 MB. By default, the MDisks created for the  internal storage of flash memory in the IBM FlashSystem 9100 are created with an extent  size of 1024 MB. To use a value that differs from the default requires the use of CLI  commands to delete and re-create with different value settings. For information about the  use of the CLI commands, search for CLI commands in IBM Knowledge Center. Chapter 4. Planning  103 Extent size GLYPH<SM590000> A storage pool is a collection of MDisks. An MDisk can only be contained within a single  storage pool. GLYPH<SM590000> IBM FlashSystem 9100 can support up to 1,024 storage pools. GLYPH<SM590000> The number of volumes that can be allocated per system limit is 10,000. GLYPH<SM590000> Volumes are associated with a single storage pool, except in cases where a volume is  being migrated or mirrored between storage pools.