Apologies if you get this twice - the first one didn't seem to make it... Hi Guys, I have just replaced a faulty Max...woah, wait...this one's a Seagate... IDE hard disk but I cannot remake the software raid pair. The currently running disk is hda and I am trying to add back hdg - both are master drives on separate controllers. I have run fdisk on hdg and created the same partition structure as had and changed their types to 'fd' but when I try and rebuild the array I get: mdadm /dev/md0 -a /dev/hdg1 mdadm: hot add failed for /dev/hdg1: Invalid argument If I look at /var/log/messages, I have: Oct 5 16:04:39 petdoctors kernel: md: could not bd_claim hdg1. Oct 5 16:04:39 petdoctors kernel: md: error, md_import_device() returned -16 >From other postings, this seems to imply the hdg1 partition is mounted but I can find no evidence of this (df or cat /proc/mounts or lsof). I have done sone googling and found others having fun with this but no specific solution. Anyone? Thanks Nigel Kendrick