I am running TrueNAS scale and have a Mirror VDEV with two drives.
I need to replace the original drives with larger drives (18TB each). I have done a Replace on the first replacement drive, and it is busy resilvering.
When I replace the second drive, and it has finished resilvering I would expect it by default to resize the pool to have the full capacity of 18TB.
Is this correct?
Will zfs expand the drive to the entire capacity to the last byte, or will it reserve a few MB (or GB) to account for any future drive replacements that may have the same capacity on the label but differ by a few MB? I once ran into this issue.
My original disk have a 2GB swap partition that I think TrueNAS may have created. The replacement 18TB disk (replaced using the Replace function in the Web UI) seems to be just have a single ZFS partition.
Does anyone have any advice. I am unsure how to proceed. I have stopped the resilvering. I am concerned that without a 2gb swap partition, if I never need to do an emergency drive replacement and the replacement drive is a byte or more smaller in actual size, I will have a problem.
It should be, yes, but SCALE seems to have a long-standing bug where the partitions on the replacement drives are created at the same size as on the originals. If you encounter this (i.e., if your pool doesn’t auto-expand), see:
Should I not worry about the fact that the replacement drive partitions to not match the original drive (new drive is automatically partitioned without a 2GB swap)?
