[CentOS] adding a usb drive to an existing raid1 set

rado rado at rivers-bend.com
Fri Sep 29 02:54:38 UTC 2006

On Thu, 2006-09-28 at 20:36 -0500, Les Mikesell wrote:
> On Thu, 2006-09-28 at 18:16, rado wrote:
> > kk...the ide drives; hda and hdc...3 partitions 3 arrays md0 1 and 2 
> > cat /proc/mdstat shows it's acting as it should.
> Are you trying to add a 3rd partition to a raid created with only
> 2?  I don't think that will work, although you could fail/remove
> an existing partition, then add the new one as a replacement.

no, no...the existing arrays already have the "3rd" partition...I just
want to add another complete drive, already partitioned exactly like the
2 that are already running. No extras there...just another drive.
> > when I boot the system up, it sees the drive connect thru usb and calls
> > it sda (for what reason I don't know. I partitioned it to the same specs
> > as the 2 ide drives as per the bottom of fdisk -l. 
> USB/firewire drives are assigned the next available scsi device
> name as detected - doesn't make much sense to me either...
> > ummm...1.)I think this is part of the old raidtools thang...not mdadm
> > but I am not sure.
> > 	2.) there is no man raidtab on this box which is a "everything"
> > install..
> Raidtab isn't used any more - it's all mdadm commands.
exactly and there is a ton of stuff out there about raidtab grrrr
and for 2 or 3 versions now it's all been mdadmin and rh still talks
about raidtab in there docs...but I guess if that's the only thing wrong
w/rh then we in pretty good shape.
> > kk, right now...I just formatted all the partitions and (I should have
> > done this before ) I am checking for bad blocks. If it finds some I'll
> > just redo it or whatever I have to do. At one point I was able to
> > mdadm /dev/md0 1 & 2 --add sda1 2 &3 and 
> > cat /proc/mdstat would show sda1 2 &3 as in the arrays but then they
> > would not populate.
> It's only going to rebuild the number of devices you gave
> in the create command (or whever disk druid set up if you
> did it that way).  I'm not sure if there is any way to change
> that later.
oh, c'mon Les, don't tell me that!!! geez!
kk, I have not found it yet but I'm looking for some way to first add a
spare to the existing raid sys...then go for it.
hint hint lol. geez I dunno!

another thing that bothers me is that, just for the hell of it I started
a new install. went to disk druid and the usb (sda) never was an option;
like it never/doesn't exist. so of course I just backed out of it.

there has to be a way. I'm sure there is, you are doing the exact same
thing I am trying to do!

thx Les,

John Rose

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