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RE: Soft-Raid Testing and other stuff...



Hello,

> -----Original Message-----
> From: redhat-list-bounces redhat com 
> [mailto:redhat-list-bounces redhat com] On Behalf Of Richard Hobbs
> Sent: 20 January 2005 11:08
> To: 'General Red Hat Linux discussion list'
> Subject: RE: Soft-Raid Testing and other stuff...
> 
> Hello,
> 
> > -----Original Message-----
> > From: redhat-list-bounces redhat com 
> > [mailto:redhat-list-bounces redhat com] On Behalf Of Richard Hobbs
> > Sent: 20 January 2005 10:02
> > To: 'General Red Hat Linux discussion list'
> > Subject: RE: Soft-Raid Testing and other stuff...
> > 
> > Hello,
> > 
> > > > I have built two RedHat 8.0 machines, both using soft-raid 
> > > to mirror one
> > > > 250GB disk onto the other identical 250GB disk inside the case.
> > > > 
> > > > During the install, I created the RAID partitions, and 
> > > assigned them to
> > > > actual partitions, and now I have "/dev/md0" up to "/dev/md7".
> > > > 
> > > > However, each time I boot and each time I shut down, I get 
> > > the following
> > > > message:
> > > > 
> > > >   No spare disk to reconstruct array! -- running in 
> degraded mode.
> > > > 
> > > > What exactly does this mean? Both drives are visible from 
> > > the BIOS, and the
> > > > jumpers are set to Cable Select (not Master and Slave).
> > > > 
> > > > Despite the above error message, the machine boots fine, 
> > > shuts down fine,
> > > > and runs fine.
> > > 
> > > When it's up, cat /proc/mdstat
> > 
> > --------------------------------------------------
> > [root stg-slave root]# cat /proc/mdstat
> > Personalities : [raid1]
> > read_ahead 1024 sectors
> > md7 : active raid1 hda9[0]
> >       71296320 blocks [2/1] [U_]
> > 
> > md3 : active raid1 hda8[0]
> >       2096384 blocks [2/1] [U_]
> > 
> > md4 : active raid1 hda7[0]
> >       10482304 blocks [2/1] [U_]
> > 
> > md6 : active raid1 hda6[0]
> >       73400832 blocks [2/1] [U_]
> > 
> > md5 : active raid1 hda5[0]
> >       73400832 blocks [2/1] [U_]
> > 
> > md2 : active raid1 hda3[0]
> >       7164864 blocks [2/1] [U_]
> > 
> > md1 : active raid1 hda2[0]
> >       7164864 blocks [2/1] [U_]
> > 
> > md0 : active raid1 hda1[0]
> >       104320 blocks [2/1] [U_]
> > 
> > unused devices: <none>
> > [root stg-slave root]#
> > --------------------------------------------------
> >  
> > > > However, if I unplug the master hard drive, it will not 
> > > boot from the
> > > > secondary, even if I plug it into the primary socket on the 
> > > IDE cable.
> > > 
> > > Did you duplicate the MBR to the second drive?  If you 
> > > didn't, you won't
> > > boot.  Remember that you've only mirrored the data 
> > partitions, not the
> > > boot block.
> > 
> > I didn't duplicate the MBR as far as I know... I assumed that RAID 1
> > (mirroring) mirrored the entire disk, sector for sector...
> > 
> > If I duplicate the MBR successfully, does that mean I should 
> > be able to
> > simply remove the primary, and boot from the secondary alone?
> > 
> > Also, if I then insert a blank disk, will it automatically 
> > re-generate the
> > data onto it? Will I have to duplicate the MBR manually again?
> > 
> > Finally, how can I duplicate the MBR onto the secondary disk?
> > 
> > > > I have even tried inserting a third 250GB hard drive on the 
> > > secondary IDE
> > > > channel to see if that would become the spare disk it needs 
> > > to reconstruct
> > > > the array, but that didn't work either.
> > > 
> > > I wouldn't expect it to.  I would not be happy if the 
> software just
> > > grabbed an extra drive and toasted the data on it unless I 
> > explicitely
> > > told it to.
> > 
> > Very true... It was a last ditch attempt to eliminate that 
> if nothing
> > else... Lol
> > 
> > Thanks for your help Ed... I look forward to hearing from you 
> > again soon :-)
> > 
> > Hobbs.
> 
> I have just found this web page...
> 
>   http://www.kieser.net/linux/raidhotadd.html
> 
> ...and I'm currently following the instructions on it. So 
> far, I have typed:
> 
>   > raidhotadd /dev/md1 /dev/hdb2
>   > raidhotadd /dev/md0 /dev/hdb1
>   > raidhotadd /dev/md2 /dev/hdb3
>   > raidhotadd /dev/md5 /dev/hdb5
>   > raidhotadd /dev/md6 /dev/hdb6
>   > raidhotadd /dev/md4 /dev/hdb7
>   > raidhotadd /dev/md3 /dev/hdb8
>   > raidhotadd /dev/md7 /dev/hdb9
> 
> The current output from /proc/mdstat is:
> 
> --------------------------------------------------
> 
> --------------------------------------------------
> 
> This is looking more promising, but I don't think it's doing the MBR
> still... Perhaps soft-raid doesn't work under RH8 as 
> standard, otherwise it
> wouldn't boot the disks from the array and cause me to have 
> to manually
> re-add them...
> 
> I shall keep you updated on how this goes.
> 
> Hobbs.

Oops... I meant to say that the output from /proc/mdstat is:

--------------------------------------------------
[root stg-slave root]# cat /proc/mdstat
Personalities : [raid1]
read_ahead 1024 sectors
md7 : active raid1 hdb9[2] hda9[0]
      71296320 blocks [2/1] [U_]
      [>....................]  recovery =  2.8% (2040792/71296320)
finish=111.7min speed=10323K/sec
md3 : active raid1 hdb8[2] hda8[0]
      2096384 blocks [2/1] [U_]

md4 : active raid1 hdb7[2] hda7[0]
      10482304 blocks [2/1] [U_]

md6 : active raid1 hdb6[2] hda6[0]
      73400832 blocks [2/1] [U_]

md5 : active raid1 hdb5[2] hda5[0]
      73400832 blocks [2/1] [U_]

md2 : active raid1 hdb3[2] hda3[0]
      7164864 blocks [2/1] [U_]

md1 : active raid1 hdb2[1] hda2[0]
      7164864 blocks [2/2] [UU]

md0 : active raid1 hdb1[2] hda1[0]
      104320 blocks [2/1] [U_]

unused devices: <none>
[root stg-slave root]#
--------------------------------------------------

Hobbs.

-- 
Richard Hobbs (Systems Administrator)
Toshiba Research Europe Ltd. - Speech Technology Group
Web: http://www.toshiba-europe.com/research/
Email: richard hobbs crl toshiba co uk
Tel: +44 1223 376964        Mobile: +44 7811 803377



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