[Eclug] Debian no longer recognized partitions

Ok, its reassuring to know I can follow up on these steps without risking 
permanent damage.  I was prepared to spend my morning fiddling with mknod, 
but as I was searching online for the correct major and minor device codes I 
came across a post that suggested using hdparm -z to force the kernel to 
reread the partitions.  I ran it on each device and it located the 
partitions perfectly.  A quick rebuild of the array and I'm back in 
business.  Thanks again for all the advice Jason and Rohit.

>From: Jason Gurtz <jason at jasongurtz.com>
>Reply-To: "Eastern Connecticut Linux Users' Group" <eclug at lists.eclug.net>
>To: "Eastern Connecticut Linux Users' Group" <eclug at lists.eclug.net>
>Subject: Re: [Eclug] Debian no longer recognized partitions
>Date: Fri, 17 Nov 2006 13:23:29 -0500
>
>On 11/17/2006 11:04, Chacko Cherackal wrote:
> > If this doesn't work I'm going to try Jason's suggestion of forcing
> > recognition using mknod.  I'm holding off to use that as a last resort
> > because it seems like something I could use to muck things up even 
>further.
>
>Terminology is a bit off here...  All mknod does is create files[1]
>there is no "recognizing" or anything like that going on.  UDEV and
>similar are the ones that do auto-recognition.  As you're finding out,
>this type of modern functionality is not very long in the tooth.  This
>manual device creation also used to be handled by a script (even an
>executable in some cases) called MAKEDEV.  I believe that MAKEDEV was a
>redhat invention, eons ago.  One problem (besides extreme pain in
>dealing with dynamic hotpluggable hardware) with manual device node
>creation is that the /dev directory was typically cluttered with
>hundreds of nodes that pointed to hardware that didn't even exist in the
>system.  The worst offender was probably the dozens and dozens of serial
>ports, left from the days of many serial terminals operating off of one
>server.  With dynamic detection and creation, what you see is what you
>have, unless it doesn't work, which leads to your situation.[2]
>
>If you make a mistake using mknod, you won't have screwed anything up,
>and can just delete the files you have created.  I think, but am not
>sure, that you may be able to create these device files not just in
>/dev, but anywhere you want "just in case" (e.g. create /root/dev/sda1
>etc...)  Then it's just a matter of using your software raid tools to
>tie together those device files that you created
>
>~Jason
>
>--
>[1]  OK OK they're device pointers and not *really* files in the sense
>that they contain data.  They are however, just files as far as the
>filesystem is concerned (e.g. you can ls/rm/cat/echo "foo" > to/from
>them just like any other file). NOTE: doing some of those things NOT
>necessarily recommended!
>
>[2] Trivia: Windows has had this dynamic device creation and
>coresponding device nodes for quite some time.  If you dig into the
>kernel API, you can find such things as \Device\Harddisk1 and so on.  If
>you look at OpenVMS (red-headed stepfather to NT), you will see these
>same names...  As is so painfully typical under windows, the user can
>not directly interact with these special files, as one can under Linux.

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