A detailed walkthrough of migrating 18 TB of data from a 4-disk RAIDZ1 ZFS pool to a 7-disk RAIDZ2 pool using only three additional disks. The process involves creating a temporary RAIDZ2 pool with a sparse file as a fake disk, migrating data using ZFS snapshots, destroying the old pool, and expanding the new pool with the remaining disks. The migration leverages ZFS's new RAIDZ expansion feature available in OpenZFS 2.3.0 and TrueNAS 25.04.
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How I did it 🔗︎Why switch from RAIDZ1 to RAIDZ2? 🔗︎Why is switching from RAIDZ1 to RAIDZ2 hard? 🔗︎Migrating from RAIDZ1 to RAIDZ2: in practice 🔗︎My complete 7x8TB RAIDZ2 pool 🔗︎43 Impressions