In Dell UnityOS version 4.3 and later, data reduction is supported on Thin LUNs, Thin LUNs within a Consistency Group, Thin File Systems, and Thin VMware VMFS and NFS Datastores. To support data reduction, Thin File storage resources must be created on Dell UnityOS version 4.2 or later and be created within an All Flash Pool. File storage resources created on Dell UnityOS versions prior to version 4.2 do not support data reduction. Within a Consistency Group, data reduction enabled LUNs can be mixed with LUNs which have data reduction disabled. In Dell UnityOS 4.5 and later, Advanced Deduplication is included as an optional feature to the Data Reduction algorithm for configurations that support it.

In Dell UnityOS 5.2 and later, hybrid (mixed drive type) pools created on Unity XT model systems also support Data Reduction with and without Advanced Deduplication enabled. The pool type can either be Traditional or Dynamic. To support Data Reduction, the pool must contain a flash tier and the total usable capacity of the flash tier must meet or exceed 10% of the total pool capacity. Once a system is upgraded to UnityOS version 5.2 or later, Data Reduction can be enabled on an existing resource if the flash capacity requirement is met.

0 below outlines the supported configurations for Data Reduction and Advanced Deduplication.

Table 1. Supported Configurations for Data Reduction and Advanced Deduplication

1 Resource can be created on either a Traditional or a Dynamic Pool (For systems that support Dynamic Pools)

2 Resource can be created on a Dynamic Pool Only

3 The pool must contain a flash tier and the total usable capacity of the flash tier must meet or exceed 10% of the total pool capacity

Dell Unity Data Reduction and the Advanced Deduplication option, for configurations supporting the Advanced Deduplication feature, can be enabled on supported storage resources at the time of the resource’s creation, or enabled or disabled at a later time. Advanced Deduplication requires Data Reduction to be enabled on the resource but can be enabled or disabled independently to the Data Reduction setting. Local LUN Move can be leveraged to move a resource’s data into a data reduction, and optionally an Advanced Deduplication enabled resource. For File storage resources, there is no direct method available to convert from a Thick File resource or pre-Dell UnityOS 4.2 Thin File resource to a 4.2 or later Thin File resource. Methods to move File data include host-based migration to a Dell UnityOS 4.2 or later Thin File System, VMware vMotion for VMs created on NFS Datastores, or Dell Unity Asynchronous Replication. More information about migration options can be found in the Dell Unity: Migration Technologies white paper found on Dell Technologies Info Hub.

Dell Unity Data Reduction can also be enabled on Block and File storage resources participating in replication sessions. The source and destination storage resources in a replication session are completely independent, and data reduction with or without the Advanced Deduplication option can be enabled or disabled separately on the source and destination resource. The availability of enabling data reduction, Advanced Deduplication, or compression, in the case of codes prior to Dell UnityOS version 4.3, on a source and/or a destination resource depends on the Dell UnityOS version, the system type, and the Pool configuration.

In UnityOS versions prior to the 5.2 release, All Flash Pools containing data reduction enabled storage resources cannot be expanded with SAS or NL-SAS drives. In UnityOS version 5.2 and later, expansion is supported as along as the 10% Flash Capacity requirement is not violated. The pool expansion process will not proceed if the percentage of flash capacity within the resulting pool will be less than 10%. For more information about expanding Pools and how to convert to a Hybrid Flash Pool, please review the Pool Expansion section found under Interoperability.