fwd: Re: adding a drive to linear raid]

[Gregory Nowak]

Hi all.

I'm posting the following so that it gets into the archives, just in case some one runs into the same raid situation which I asked about a couple of days ago.

I'm all set now (smile).
This will probably ring a bell for Kirk too (smile).

Greg



----- Forwarded message from Jakob Oestergaard <jakob at unthought.net> -----

Date: Fri, 8 Nov 2002 11:09:55 +0100
From: Jakob Oestergaard <jakob at unthought.net>
To: Gregory Nowak <greg at romuald.net.eu.org>
Subject: Re: adding a drive to linear raid

On Thu, Nov 07, 2002 at 01:17:38PM -0600, Gregory Nowak wrote:
> Dear Mr. OEstergaard.
> 
> Thanks to your fairly well written straight-to-the-point software raid HOWTO, I have recently successfully setup linear raid on my system with the 2.4.19 kernel.

Thank you  :)

> 
> I am writing to you directly, since your HOWTO doesn't seem to contain information on how one can subscribe to the linux-raid list, or where one can go to view the archives.

The list address is  linux-raid at vger.kernel.org

You will find information about it from www.kernel.org (somewhere)

> 
> When setting up my raid, I originally made hda2 and hdb2 into the md0 device, with my system temporarily stored on hde2.
> 
> After successfully transferring the system over to md0 from hde2, I now would like to add hde2 to be a part of md0.
> 
> I have marked the hde2 partition as type FD, and have modified my /etc/raidtab. 
> However, when I boot, I get the following.
> 
> 
> md: linear personality registered as nr 1
> md: md driver 0.90.0 MAX_MD_DEVS=256, MD_SB_DISKS=27
> md: Autodetecting RAID arrays.
>  [events: 00000044]
>  [events: 00000044]
>  [events: 00000000]
> md: invalid raid superblock magic on hde2
> md: hde2 has invalid sb, not importing!
> md: could not import hde2!
> md: autorun ...
> md: considering hdb2 ...
> md:  adding hdb2 ...
> md:  adding hda2 ...
> md: created md0
> md: bind<hda2,1>
> md: bind<hdb2,2>
> md: running: <hdb2><hda2>
> md: hdb2's event counter: 00000044
> md: hda2's event counter: 00000044
> md0: max total readahead window set to 124k
> md0: 1 data-disks, max readahead per data-disk: 124k
> md: updating md0 RAID superblock on device
> md: hdb2 [events: 00000045]<6>(write) hdb2's sb offset: 9743296
> md: hda2 [events: 00000045]<6>(write) hda2's sb offset: 6201024
> md: ... autorun DONE.
> 
> 
> I was told by someone that it is possible to add new partitions to an existing linear raid, but he has forgotten how it is done.

You need to "mkraid -f" the array again, with the new raidtab.

Don't worry, it will not destroy your data, if you are running linear
mode.

> 
> I would greatly appreciate it if you could please tell me how to do this, or point me to where I can find this information.

You probably need to boot from a rescue disk (you must umount the
filesystem on the array in order to re-create it).

Then you can mkraid -f the array, with the new raidtab.

After that, run resize2fs, to actually re-size the filesystem
(otherwise, you will have the original sized filesystem on a larger
array, which will not give you any more space on the filesystem).

Now, reboot, knock-the-wood, cross fingers,  things should come up just
fine  :)


-- 
................................................................
:   jakob at unthought.net   : And I see the elder races,         :
:.........................: putrid forms of man                :
:   Jakob ?stergaard      : See him rise and claim the earth,  :
:        OZ9ABN           : his downfall is at hand.           :
:.........................:............{Konkhra}...............:

----- End forwarded message -----