Bottom Line: Do Not Start a 4-to-6 Disk Expansion by Formatting the Existing Pool
The safe order is: identify the current pool type → check whether that layout supports expansion → migrate managed ZimaOS data if required → expand or rebuild only after the data has a verified destination. The 2025 thread's advice to always rebuild the pool is no longer a reliable current rule.
Current ZimaOS Can Expand Some Storage Layouts
The September 2026 ZimaOS storage setup guide says RAID 5 can grow by adding drives and that USB drives can be used as storage, added to an array or used to expand existing space. The RAID options guide is the place to confirm the specific array type before making changes.
That is materially different from the December 2025 forum reply that described every pool change as backup, rebuild and restore.
Move Docker and User Data With Data Migration, Not Guesswork
If the disks you want to change currently hold Docker images, app data, Gallery, Downloads, Documents, Media or Backup, use the current Data Migration tool first. It can move Docker images, Docker application data and user folders at category level.
The ZimaOS migration path guide explains why moving an ordinary folder in Files is not the same as migrating ZimaOS-managed data.
When a Rebuild Is Still the Right Answer
If your current RAID level cannot grow into the layout you want, or you are changing filesystem/storage architecture, then backup → verify → rebuild → restore remains the clean approach. Do not use formatting as the first diagnostic step.
The OpenZFS documentation is the upstream reference if you are intentionally moving to ZFS, and the lsblk manual is useful for identifying disks before any destructive operation.
A Safer 4-to-6 Disk Checklist
- Record the current RAID level and all disk serial numbers.
- Back up irreplaceable files before changing the pool.
- Move managed app/user data with Data Migration if the target disks must be repurposed.
- Use the current Storage UI for supported expansion.
- If a rebuild is required, verify the backup before formatting anything.
For hard recovery cases, the ZimaOS RAID recovery guide shows why preserving metadata and verified copies matters.
