So I'm in the process of slowly converting my 19 drives array to xfs and I've found this scenario:

 

- disk18 is 2TB with no files at all on it

- I have a 4TB drive that I'd like to replace the 2TB disk18 with

- I'd like disk18 to also be formatted with xfs

 

The way I know how: (step 1 and 2 is interchangeable)

1. Replace disk18 with the 4TB disk, let parity rebuild (the already empty) disk18

2. Change the filesystem to xfs and format it

 

The downside is that I need to rebuild parity even though disk18 has no data on it. I know that the drive is not zero-ed out, at this point... but what if, preclear_disk.sh has a mode that preclears disk in-array (after the disk is unmounted) and we also preclear the new replacement disk... wouldn't that let you swap the (both zero-ed) drives in place?

 

 

2TB is RFS with no data and parity is valid.

 

Disk rebuilt but parity not rebuilt:

1. Change empty RFS 2TB to XFS and reformat.

2. Rebuild empty XFS 2TB onto 4TB.

 

or

 

Disk rebuilt but parity not rebuilt:

1. Rebuild empty RFS 2TB onto 4TB.

2. Change empty RFS 4TB to XFS and format.

 

or

 

Parity rebuilt but disk not rebuilt:

1. Replace 2TB with 4TB.

2. New config and rebuild parity.

3. Format 4TB as XFS.

 

Any of these should produce the same result.

 

Or have I misunderstood?

 

Thanks trurl.

 

I guess I was looking for ways that involves less resource suck

(running all 19 drives for 12+ hours for rebuild, slowing down transfers, etc) and/or to minimize the time that array is vulnerable without redundancy.

 

This is a fairly special case, since the drive to replace has 0 data on it and the drive to replace it can also be prepared beforehand, similar to adding precleared blank drives.

The problem is that a formatted drive is not a clear drive, since it has file system structures on it.

 

There was some discussion about using dd to zero a drive in the array, thus clearing it while maintaining parity. See these:

 

EMPTY and Remove a Drive Without Losing Parity

 

Removing multiple drives

Thanks, those are exactly it.