ysss Posted May 4, 2015 Share Posted May 4, 2015 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? Quote Link to comment
trurl Posted May 4, 2015 Share Posted May 4, 2015 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? Quote Link to comment
ysss Posted May 4, 2015 Author Share Posted May 4, 2015 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. Quote Link to comment
trurl Posted May 4, 2015 Share Posted May 4, 2015 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 Quote Link to comment
ysss Posted May 4, 2015 Author Share Posted May 4, 2015 Thanks, those are exactly it. Quote Link to comment
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