Is Inline Data Compaction Orthogonal to Inline Data Deduplication?

nachin — Wed, 04 Jun 2025 16:11:08 GMT

Dear all,

I have been very excited about the inline data compaction feature in ONTAP 9. I read Tech ONTAP and TR4476 and learnt that inline deduplication is orthogonal to inline compaction, which means inline deduplication and online compaction can be both enabled, but a block is inline deduplicated is not compacted.

https://www.netapp.com/us/media/tr-4476.pdf (Page 12)

http://community.netapp.com/t5/Tech-OnTap-Articles/A-Look-Inside-NetApp-Inline-Data-Compaction/ta-p/122362 (search for "orthogonal")

Why are this two features so mutually exclusive? Is there any nature or reason of inline dedupliation that prevents a deduplicated block from being compacted?

Any comment would be appriciated.

Re: Is Inline Data Compaction Orthogonal to Inline Data Deduplication?

asulliva — Fri, 06 Jan 2017 19:59:06 GMT

Hello @nachin,

If the block is (inline) deduplicated then it's never written to disk...the metadata is simply updated to reference the block that already exists.

Hope that helps.

Andrew

topic Is Inline Data Compaction Orthogonal to Inline Data Deduplication? in ONTAP Discussions

Is Inline Data Compaction Orthogonal to Inline Data Deduplication?

Re: Is Inline Data Compaction Orthogonal to Inline Data Deduplication?