[ale] Just an FYI share

[JD]

Your experience is seen a few times every month on the Ubuntu Forums.

RAID tools, definitely mdadm, leave RAID information on the drive in the form of
a superblock, so to reuse a drive, we need to remove that "RAID" tag from the
physical disk.  I think mdadm has an option to do it, though I've never had an
issue reusing former mdadm RAID HDDs in other systems.  --zero-superblock seems
to ring a bell for me.  As usual, check the man page for your specific installed
tools.

OTOH, some disks like each other and really, REALLY want to stay together. Seems
sorta cool that they try so very hard. Huh?


On 06/30/2013 09:31 PM, Chuck Payne wrote:
> If you are like me and recycle things when you can. One thing to watch
> out for, that I never thought to check on. What is really written to a
> hard drive.
> 
> I had a NAS die a while back, that left me 5 health drives. While
> upgrading my server, I used one of the drives to replace a failed
> drive in my server.
> 
> Well when I went to write the file system for the drive, I kept
> getting a very strange error, that the new drive was in use by the
> system.  "WTF!", how can this be? I ran fdisk and gparted. Both
> partition the drive correct but when I when to write the file system.
> Again, I got the error that the drive was in use.
> 
> I reboot changed how my SATA drive acted from IDE to ACHI, since I
> don't have any more IDE in the server.  I tried again. Same error.
> Well I looked in dmesg saw the drive, but I saw that the first slice
> was in use by soft raid  (md).  Say what? Sure enough I cat /proc/md
> and there it was. Again, excuse the use, but "WTF!".
> 
> When the distro I use, did a scan for existing partitions. I thought I
> had blasted all the partition, the showed was using XFS /dev/sdx1, but
> there was a hidden partition. One the OS picked up on, but fdisk and
> gpart did not. The partition, I found out was where the raid wrote the
> it information, it showed up as MD-512 on my partition tool.
> 
> I used the partition tool that comes with my distro to remove the
> hidden partition and I am able to use the drive.
> 
> I wanted to share this because, to this day I haven't seen this. My
> distro saw that hidden partition and thought, ok there is a soft raid,
> lets set it up, even though there the other four drives were missing.
> 
> So I guess next time I recycle a drive, I will use a nuke program and
> not hope that fdisk or gparted will get the drive done because it
> didn't this time.
> 
> I wanted to share this just in cause anyone else hits a drive that you
> can't write too, that you just add to a system.
> 
> I am not sure if this part 3.x kernel.
> 
> Any thoughts? Feed back is welcome.
> 
> --
> Terror PUP a.k.a
> Chuck "PUP" Payne
> 
> (678) 636-9678