> In addition, they don't actually bring that much space saving on common workloads. Most people don't have a lot of truly identical blocks of data. VM backing

> In addition, they don't actually bring that much space saving on common workloads. Most people don't have a lot of truly identical blocks of data. VM backing storage seems to be the biggest worthwhile use case, but that depends on whether snapshots and clones are used extensively. Installing 100 copies of Debian on empty VMs will likely get deduped quite a bit. But it's faster and provides almost the same benefits to install one VM, snapshot it, and produce the rest of the VMs by cloning from the snapshot. The only other case I could imagine dedup being good for is storing a lot of genomic data: https://techtransfer.universityofcalifornia.edu/NCD/25080.html https://techtransfer.universityofcalifornia.edu/NCD/25080.ht... But if the use-case is narrow enough for custom deduplication then it will probably be much more efficient than ZFS's block-based dedup.