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Re: raid question



Hi Alvin,

On Sun, Aug 17, 2003 at 02:25:39PM -0700, Alvin Oga wrote:

> > I was wondering can I set up raid when a partition is mounted?
> > e.g.  hda3 is /home and I want to set up raid1 with hdc3.  
> 
> you can do the "mirroring" ( raid1 ) of hda3 to hdc3
> 
> but if you expect to boot off hdc  when hda is removed, than it 
> probably wont work

I do not want to boot of it.
 
> and more importantly partition type should be F3 ( linux-raid )  insted of
> ext2 or ext3

I had already made 3 partions (not in use) on both disk EXT3, and made
a raid one system with it.  Now I have changed the type to FD (Linux
raid autodetec).  I could mount it also when being ext3.

Can't I use ext3 on the raid system?

> > Can I run mkraid when hda3 is in use?  I would use the following
> > raidtab:
> 
> no ...
> 
> you do mkraid /dev/md0  .. you do NOT format /dev/hda or /dev/hdc
> individually  .. other than the initial fdisk if you even need to do
> that

Hmm, I think I read in the sofware raid howto that I had to set up all
the partitions.  I now think they meant with it that I had to partion
it, but not put a filesystem on it.  Right?

Why can't one put a filesystem on it before the raid process?


> 
> > raiddev /dev/md0
> >         raid-level      1
> >         nr-raid-disks   2
> >         nr-spare-disks  0
> >         chunk-size      4
> >         persistent-superblock 0
> >         device          /dev/hda3
> >         raid-disk       0
> >         device          /dev/hdc3
> >         raid-disk       1
> 
> looks good
>  
> > Also, would I lose data?  When happens if I change the above order?
> 
> if you type the wrong commands ...
> 	- yes... you lose data on /dev/hda
>  
> order doesnt mean anything in the above
> 
> more software raid howto  ( converting from /dev/hda  to sw-raid )
> 
> 	http://www.1U-Raid5.net/HowTo

Ok thanks!  There is more info there than in the software raid howto
on tldp.org

Rudy

-- 
Rudy Gevaert                rudy@zeus.UGent.be
Web page                    http://www.webworm.org
GNU/Linux user and Savannah hacker http://savannah.gnu.org
 Only two things are infinite, the universe and human
stupidity, and I'm not sure about the former.  
 - Albert Einstein (1879-1955)



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