Does ZFS deduplicates across datasets or only inside a single dataset? In other words if I have two nearly identical volumes will they be deduplicated?

  • I would say it only affects the dataset. +1 I am curious to see what someone more experienced with zfs will say. – Rui F Ribeiro Jul 28 '17 at 6:48
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    According to Aaron Toponce: Data in the dataset is deduplicated. The data is matched against all the data in the pool, which includes data outside of that dataset. However, data in other datasets is not deduplicated. In other words, deduplication is handled per dataset, but the data that it's being deduplicated against can be any block on the pool, in or out of the dataset itself. – Thomas Jul 28 '17 at 10:07

ZFS deduplication is pool-wide. Identical blocks in all datasets that have dedup=on will be shared.

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