On Thu, May 18, 2017 at 11:49:11AM -0500, Sam Smith wrote: > Hi, > > I recently upgraded my home server to an HP ml30 tower server. It came with > a 4 drive hotplug SATA cage. I loaded two old unused drives in it and > installed Debian Stretch on it putting the drives in a software raid1 via > the debian installer. My plan was once I got the new box up and running that > I would shut off the old machine and use the drives from that, swapping them > out one at a time and letting mdadm resync. > > Before putting the new box into "production", I pulled the 2nd drive (sdb) > to see what would happen (with the machine still running). Of course mdadm > went into degraded mode with a one disk raid1. I slid the same drive back in > and it came back as /dev/sdb. Later on, after a few reboots, I pulled the > 2nd drive and swapped it with a drive from the old machine (it was also > still up and running with mdadm raid1). However this time the new drive > didn't come up as sdb, but as /dev/sdc. I set up the partitions the same as > sda but I didn't join it to the mdadm array yet. I wasn't sure if joining as > "sdc" and then on reboot having it come up possibly as "sdb" would mess up > anything so I just rebooted. On reboot it came up as "sdb" and I joined it > to the array and all was well. > > But I still need to swap the first drive (sda) and I don't really want to > have to reboot this time. So what can I do to ensure that once I pull the > old drive and put in the new one that it comes back up as "sda"? Or does > that even matter? (seems like it would..)
It doesn't matter that much. Use this: mdadm --fail /dev/md0 /dev/sda1 mdadm --remove /dev/md0 /dev/sda1 mdadm --add /dev/md0 /dev/whatever1 then check on progress with cat /proc/mdstat -dsr-
