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Re: Multiple RAID or encrypted partitions



On Fri, Sep 08, 2006 at 07:45:08PM -0500, Owen Heisler wrote:
> Yes, I had considered doing that.  And I'm sorry to keep harping on the
> same question, but I thought that RAID5 was capable of having multiple
> partitions in one array; is it?

Hmmm. I didn't think it was possible, but evidentally it is; according to
the md(4) man page:

: KERNEL PARAMETERS
: The md driver recognised several different kernel parameters.
: 
: raid=partitionable
: 
: raid=part
: 
: These  are  available in 2.6 and later kernels only.  They indicate that
: autodetected MD arrays should be created as partitionable  arrays, with
: a different major device number to the original non-partitionable md
: arrays.  The device number is listed as mdp in /proc/devices.

...and the mdadm manpage says:

:        -a, --auto{=no,yes,md,mdp,part,p}{NN}
: 
: Instruct  mdadm  to  create  the device file if needed, possibly
: allocating an unused minor number.  "md" causes a non-partitionable
: array  to  be  used.   "mdp",  "part"  or  "p" causes  a partitionable
: array (2.6 and later) to be used.  "yes" requires
: 
: [...]
: 
: For partitionable arrays, mdadm will create the device file  for the
: whole  array  and  for the first 4 partitions.  A different number of
: partitions can be specified at the end of this option (e.g.
: --auto=p7).   If  the device name ends with a digit, the partition names
: add a 'p', and a  number,  e.g.  "/dev/home1p3".  If  there  is  no
: trailing digit, then the partition names just have a number added, e.g.
: "/dev/scratch3".

I just tried this under Qemu (running Ubuntu), and it worked:

mdadm --create /dev/mdp0 --auto=mdp --level=5 --raid-devices=3 /dev/hdb1 /dev/hdc1 /dev/hdd1

It creates four partition devices, /dev/mdp0p1, /dev/mdp0p2, /dev/mdp0p3
and /dev/mdp0p4.

Might not necessarily work from the Debian installer though. Perhaps
you'll have to go into a shell window and do the above by hand...

Cheers,

Paul

-- 
Paul Dwerryhouse				| PGP Key ID: 0x6B91B584
========================================================================
A look at Ubuntu Server Edition:
http://nepotismia.com/review/ubuntu/server/6.06/



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