Can I achieve the same deduplication rate on a FlexGroup compared to a FlexVol?
​
Applies to
- ONTAP 9.8
- FlexGroup
- Storage Efficiency
Answer
No. Deduplication is done within FlexGroup constituents and not across the FlexGroup.
For example, the same file could be stored twice in the FlexGroup but on two different constituents – which means no deduplication will occur. Flex
Groups will have a lower savings rate when large files are spread out over multiple constituents compared to FlexVol volumes.
Example:
FlexVol:
There are four 100GB files in a FlexVol set up in the system:
Volume | Filename | Logical size |
vol1 | file1 | 100GB |
vol1 | file2 | 100GB |
vol1 | file3 | 100GB |
vol1 | file4 | 100GB |
Because of deduplication working on the entire volume, they would take up:
Filename | Physical size (deduplication of files) | Logical size |
file1, file2, file3, file4 | 100GB | 400GB |
Above will give us a 3:1 savings ratio.
FlexGroup:
In a FlexGroup, the files get split into multiple constituents:
Constituent | Filename | Logical size |
Const001: aggr1 | file1 | 100GB |
Const001: aggr1 | file2 | 100GB |
Const002: aggr1 | file3 | 100GB |
Const002: aggr1 | file4 | 100GB |
Now the deduplication is working on each individual constituent:
Constituent | Physical size | Logical size |
Const001: aggr1 | 100GB | 200GB |
Const002: aggr1 | 100GB | 200GB |
The combined physical size would in the above example be 200GB, as the deduplication is not done across constituents, giving us a 2:1 savings ratio.