Yorick
Wizard
- Joined
- Nov 4, 2018
- Messages
- 1,912
So now I am planning to copy the 4TB onto one disk, and create a 9-disk raidz3 array which should hopefully give me 12TB of space with 3 copies of all blocks.
Then I will copy the 4TB back onto raidz3.
There is an alternative to that. It's a little tricky, read the forums for exact guidance. What you are going to do: Phantom drive.
- Create a sparse file of 4TB
- Create a 10-wide raidz3 that uses nine (9) physical disks and one (1) sparse file
- DO NOT COPY ANY DATA ON THERE
- Offline the sparse file "disk", and delete the sparse file
- Your pool is now degraded with 2x redundancy
- Copy the 4TB onto the pool
- Bring in the 4TB drive you had your data on, tell ZFS to use it as a replacement for the "failed" sparse file drive, and wait for resilver. Tada, 10x-wide raidz3 with proper 3x redundancy.
- When building your pool and resilvering, take care to not use physical drive letters. You need UIDs, and partitioning for future replacement ease is a grand idea. This is why this gets a bit tricky: Usually TrueNAS takes care of all that, but it won't let you build a pool with sparse files. You can let it partition the drives on a 9-wide, then blow that pool away from command line, and rebuild it from CLI using UID identifiers not /dev, with the sparse file. Recommend reading up on it, having a great checklist, and doing it with an eye towards being chill with blowing it all away and redoing until the pool is exactly the way it needs to be. Then and only then put data on it.