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NetApp has a notion of

  • logical storage,
  • volume used and available space

The logical storage deviates from volume used and available space, because the used space has storage optimizations like deduplication and compression.

Does NetApp allow third party tooling to get access to the raw read-access to the potentially-deduplicated and potentially-compressed volumes?

Evan Carroll
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  • Can you clarify what you mean by "raw read-access"? Are you wanting to see what the bytes look like on disk? What would be the use case for that? – Taylor Riggan Feb 01 '23 at 07:02
  • @TaylorRiggan so you can only copy of something that is deduplicated in 5 places. – Evan Carroll Feb 01 '23 at 14:54
  • NetApp is doing deduplication, compression, and compaction at a 4KB block level. Not at a file level. This is all taking place below the filesystem. – Taylor Riggan Feb 01 '23 at 17:52
  • @Taylor That's why I want raw access to the file system... Otherwise when I go to upload a 1TB file that exists in three places, I do not know the blocks are deduplicated. So you either hash every file (tremendously wasteful, and slow, and vulnerable to TOCTOU or you upload the file three times for each place you encounter it. – Evan Carroll Feb 01 '23 at 18:01
  • Well, you wouldn't hash the file, but the blocks would get hashed. If inline deduplication is enabled, then that would happen on ingest. There are other ways to address this. ONTAP supports file-level cloning. Would this work for your needs? https://docs.netapp.com/us-en/ontap-cli-97/volume-file-clone-create.html#description And this is pointer based, so not doing a full copy of the cloned file. – Taylor Riggan Feb 01 '23 at 18:19
  • I don't want it to happen on ingest because that means transferring hundreds of gigabytes to a remote machine which then has to calculate that the underlying blocks are duplicate. I want a method to query the file system and find that out. – Evan Carroll Feb 01 '23 at 21:47
  • That makes sense. What about the use of the file-level cloning feature? Is that more of what you're looking for? – Taylor Riggan Feb 02 '23 at 02:15

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