Re: Partitioned raid and major number

On 2004.02.27 02:17, Neil Brown wrote:

On Friday February 27, neilb@cse.unsw.edu.au wrote:

quoted

Right.  I missed a bit in the patch.
(I assume you are still wanting to boot off /dev/sda until you copy
the data into /dev/md/d0p* - then you will use root=/dev/md_d0p1)

Sorry, that patch was wrong.
This one, ontop of the original patch, works for me (I finally got
around to testing it).

Yes, it works! Great.

Now how to enable RAID1 on an existing disk... I hoped that I could create
an array with /dev/sda and /dev/sdb, with /dev/sdb marked as failed-disk.
Because initializing a RAID1 array with just one working disk doesn't
destroy the existing contents of the disk, right ? (I kept the last few
MB of the disk as free space for the raid superblock).

Unfortunately the current tools (or the kernel) doesn't let me do that
(/dev/sda is busy).

Two more minor issues - one, if partitioned MD is on (/dev/md/d0 etc)
the standard /dev/md0 device doesn't work anymore. For accessing the whole
device (management purposes / tools) shouldn't both /dev/md0 and
/dev/md/d0 open the same device ?

Two, shouldn't raid=partitionable md=d0,/dev/sda,/dev/sdb simply be
md=d0,/dev/sda,/dev/sdb,partitionable ? You could even leave out the 'd'
then and make it md=0,/dev/sda,/dev/sdb,partitionable. Together with
(one) this would make a bit more sense.

I hope to figure out how to migrate an existing 1-disk setup to RAID1 on
a live machine over the weekend.

Mike.