QCOW2 on ZFS, but over NFS?

mambojuice

New Member
Aug 15, 2025
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We all know that a COW disk on a COW filesystem is bad, but what if the underlying storage is over NFS?

I haven't been able to find a definitive answer, but I would imagine that QCOW2 disk images on NFS storage should be safe from write amplification even if the underlying NFS storage is ZFS.

Wouldn't the QCOW2 copy-on-write occur on the PVE host, while the raw storage copy-on-write happens on the ZFS box? Or am I way off in my assumption?