Soft-Raid Testing and other stuff...
Gavin McDonald
gavitron at gmail.com
Wed Apr 20 18:22:57 UTC 2005
cat /proc/mdstat
-G
-----Original Message-----
From: redhat-list-bounces at redhat.com [mailto:redhat-list-bounces at redhat.com]
On Behalf Of Richard Hobbs
Sent: Wednesday, April 20, 2005 4:42 AM
To: 'General Red Hat Linux discussion list'
Subject: RE: Soft-Raid Testing and other stuff...
Hello,
Sorry to drag up an old topic, and sorry again for top posting, but this
question is related, but not directly...
If a drive dies in a RH8.0 Soft-RAID configuration, will I ever be notified?
Will an email ever get sent? Or, will I need to write a script and put it
into cron which checks the status and reports if it's bad?
If I need to write a custom script, what command can I manually type in
which will give me the status of the array in terms of dead disks etc...?
Thanks in advance,
Hobbs.
--
Richard Hobbs (Systems Administrator)
Toshiba Research Europe Ltd. - Speech Technology Group
Web: http://www.toshiba-europe.com/research/
Email: richard.hobbs at crl.toshiba.co.uk
Tel: +44 1223 376964 Mobile: +44 7811 803377
> -----Original Message-----
> From: redhat-list-bounces at redhat.com
> [mailto:redhat-list-bounces at redhat.com] On Behalf Of Richard Hobbs
> Sent: 21 January 2005 17:02
> To: 'General Red Hat Linux discussion list'
> Subject: RE: Soft-Raid Testing and other stuff...
>
> Hello,
>
> > -----Original Message-----
> > From: redhat-list-bounces at redhat.com
> > [mailto:redhat-list-bounces at redhat.com] On Behalf Of Richard Hobbs
> > Sent: 20 January 2005 14:23
> > To: 'General Red Hat Linux discussion list'
> > Subject: RE: Soft-Raid Testing and other stuff...
> >
> > Hello,
> >
> > > -----Original Message-----
> > > From: redhat-list-bounces at redhat.com
> > > [mailto:redhat-list-bounces at redhat.com] On Behalf Of Ed Wilts
> > > Sent: 20 January 2005 12:53
> > > To: General Red Hat Linux discussion list
> > > Subject: Re: Soft-Raid Testing and other stuff...
> > >
> > > On Thu, Jan 20, 2005 at 11:17:01AM -0000, Richard Hobbs wrote:
> > > > > > I didn't duplicate the MBR as far as I know... I
> > > assumed that RAID 1
> > > > > > (mirroring) mirrored the entire disk, sector for sector...
> > >
> > > Nope - it's partition by partition. That's why you did the
> > raidhotadd
> > > *per partition*.
> > >
> > > There are pros and cons to this approach - the biggest pro
> > is that you
> > > don't have to mirror the entire disk. The biggest con is
> > > that only data
> > > partitions are mirrored.
> > >
> > > For details on mirror the mbr, see:
> > > http://www.dur.ac.uk/a.d.stribblehill/mirrored_grub.html
> > >
> > > I haven't tried this but it's referenced by the online Red Hat
> > > documentation.
> > >
> > > > > > 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?
> > > > > >
> > >
> > > You will always have to do this manually. Software RAID
> > knows nothing
> > > about the MBR - only partitions.
> >
> > So... am I correct in saying that if I run 'raidhotadd' on
> > all partitions to
> > get them mirrored correctly, and then I run the grub stuff to
> > install the
> > slave MBR, all is set and there's absolutely nothing else
> > that needs to be
> > done? In order to have a fully resilient system?
> >
> > I realise the BIOS might need to be altered to tell it to
> > boot from the
> > slave if the master is dead, but apart from that, is
> > everything done that
> > needs to be?
> >
> > Also, what are the exact steps to follow if the master disk
> dies in a
> > soft-raid 1 environment?
> > What are the steps to follow if the secondary disk dies in a
> > soft-raid 1
> > environment?
> >
> > I assume they are fairly similar... Just replace the dead
> disk with an
> > identical blank one, boot up and reinstall the MBR once the
> automatic
> > reconstruction is done, right?? Or is it not that simple...
> >
> > Thanks again,
> > Hobbs.
>
> I have now solved this problem completely, so thanks to Ed Wilts and
> SpookyEddy from TechIMO.com.
>
> The answer was basically that I have to mirror the partitions
> independantly,
> and I have to duplicate the MBR.
>
> Also, if a disk fails, I have to manually re-create the
> partitions on the
> blank disk exactly as they are on the working disk.
>
> The full answer can be found here:
>
> http://unixforum.co.uk/667.html
>
> Thanks to all :-)
>
> Hobbs.
>
> --
> Richard Hobbs (Systems Administrator)
> Toshiba Research Europe Ltd. - Speech Technology Group
> Web: http://www.toshiba-europe.com/research/
> Email: richard.hobbs at crl.toshiba.co.uk
> Tel: +44 1223 376964 Mobile: +44 7811 803377
>
>
>
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