Home > Storage > Unity XT > Virtualization, Cloud & Applications > Dell EMC Unity: VMware vSphere Best Practices > Storage pools
As of Dell Technologies Unity OE version 5.4, Dell Technologies Unity supports two types of storage pools on all-flash storage systems: traditional pools and dynamic pools. Traditional pools apply RAID protection to discrete groups of drives within the storage pool. Dynamic pools apply RAID to groups of drive extents from drives within the pool and allow for greater flexibility in managing and expanding the pool. Dynamic pools must be configured from all-flash drives; dynamic pools cannot be built with HDDs.
In general, it is recommended to use a small number of storage pools within Dell Technologies Unity storage to reduce complexity and increase flexibility. However, it may be appropriate to configure additional storage pools in the following cases:
Storage pool capacity is used for multiple purposes:
Storage pools must maintain free capacity to operate properly. By default, Dell Technologies Unity systems will raise an alert if a storage pool has less than 30% free capacity and will begin to automatically invalidate snapshots and replication sessions if the storage pool has less than 5% free capacity. Dell Technologies recommends that a storage pool always has at least 10% free capacity.
All-flash pools provide the highest level of performance in Dell Technologies Unity arrays. Use an all-flash pool when the application requires the highest storage performance at the lowest response time.
•Dell Technologies FAST™ Cache and FAST VP are not applicable to all-flash pools.
•Compression is only supported on an all-flash pool.
•Snapshots and replication operate most efficiently in all-flash pools.
•Dell Technologies recommends using only a single drive size and a single RAID width within an all-flash pool.
For example, for an all-flash pool, use only 1.6 TB SAS flash 3 drives and configure them all with RAID 5 8+.
Hybrid pools are not applicable when using Dell Technologies Unity All-Flash arrays.