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Dell Unity compression reduces the amount of physical storage needed to save a dataset in an all-flash pool for block LUNs and VMFS datastores. This capability was added to Dell Unity OE version 4.1 for thin block storage resources and was called Dell Unity Compression. Thin file storage resource support was added in Dell Unity OE version 4.2 for file systems and NFS datastores in an all-flash pool.
In Dell Unity OE version 4.3, the Dell Unity Data Reduction feature replaces compression. It provides more space-savings logic to the system with the addition of zero-block detection and deduplication. In Dell Unity OE version 4.5, data reduction includes an optional feature called Advanced Deduplication, which expands the deduplication capabilities of the data reduction algorithm. With data reduction, the amount of space required to store a dataset for data reduction-enabled storage resources is reduced when savings are achieved. Data reduction and advanced deduplication are supported on LUNs, file systems, NFS, and VMFS datastores. Starting with OE 4.5, an 8 KB Dell Unity block within a resource is subject to compression. The block will be compressed if a 1% savings or higher can be obtained.
Dell Unity Data Reduction savings are not only achieved on the storage resources it is enabled on, but on snapshots and thin clones of those resources. Snapshots and thin clones inherit the data reduction setting of the source storage resource, which helps to increase the space savings that they can provide.
If Dell Data Reduction is enabled, the storage system intelligently controls it. Configuring data reduction and reporting savings is simple, and can be done through Unisphere, Unisphere CLI, or REST API.
Dell Unity Data Reduction is licensed with all physical Dell Unity systems at no additional cost. Data reduction is not available on the Dell Unity VSA version of the Dell Unity platform as data reduction requires write caching within the system. Dell Unity must be at OE version 4.3 or later to use data reduction with block and file resources (thin LUNs, thin file systems, VMware vStorage VMFS datastores, and NFS).
By offering multiple technologies of space saving, Dell Unity provides flexibility for the best balance of space savings and performance.
Dell Unity OE | Dell Unity model | Dell Unity pool type | Technology |
4.3/4.4 | 300, 400, 500, 600 300F, 400F, 500F, 600F 350F, 450F, 550F, 650F | All flash* | Data reduction
|
4.5
| 300, 400, 500, 600 300F, 400F, 500F, 600F 350F, 450F, 550F, 650F | All flash* | Data reduction |
450F, 550F, 650F | All flash* | Data reduction and advanced deduplication on dynamic pools only | |
5.0 | 300, 400, 500, 600 300F, 400F, 500F, 600F 350F, 450F, 550F, 650F 380, 480, 680, 880 380F, 480F, 680F, 880F | All flash* | Data reduction |
450F, 550F, 650F 380, 480, 680, 880 380F, 480F, 680F, 880F | All flash* | Data reduction and advanced deduplication |
* Resource can be created on either a traditional or a dynamic pool (for systems that support dynamic pools).
Note: Data reduction is disabled by default and needs to be enabled before advanced deduplication is an available option. After enabling data reduction, advanced deduplication is available, but is disabled by default.
While data reduction helps to optimize storage investments by maximizing drive utilization, data reduction:
Consider these best practices before enabling data reduction on a storage object:
For additional information regarding compression and data reduction, see the Dell Unity: Data Reduction document.
Advanced deduplication, an optional extension of data reduction released in OE 4.5, increases the capacity efficiency of data reduction. Advanced deduplication can be enabled on storage and is only performed on compressed blocks. With OE 4.5, that meant that advanced deduplication would be performed on compressed blocks that sustained as little as a 1% savings or higher. In cases where a Dell Unity block did not compress, advanced deduplication would not be performed. So if there were multiple copies of an uncompressed block, deduplication would not be applied to the uncompressed multiple block copies to realize further storage savings.
This restriction of not performing advanced deduplication on blocks with less than a 1% compression savings no longer exists in OE 5.0. With OE 5.0, advanced deduplication can deduplicate to an uncompressed block whenever a write or overwrite occurs on the block even if the block has 0% compression.
For more information regarding advanced deduplication, see the Dell Unity: Data Reduction document and the Dell Unity: Best Practices Guide document.