[clug] mirroring scsi drive

nicolas.cherbuin nicolas.cherbuin at netspeed.com.au
Sat Sep 6 16:47:20 EST 2003

Thanks very much for your response. It has triggered another question 
however. Once I have created the mirror, is there a way of updating it 
automatically on a regular basis without having to boot from CD or floppy?

Thanks again


At 16:34 06/09/03 +1000, Eyal Lebedinsky wrote:
>"nicolas.cherbuin" wrote:
> >
> > Hi,
> >
> > I have an old IBM server at home with two 9.1GB scsi drives. On one I have
> > installed RH 9, on the other there is an old version (RH 7.2).
> >
> > What I am trying to do is mirroring the first one on the second one. My
> > problem is that when the two drives are inserted the computer boots on 
> RH 7.2.
> >
> > As the first drive is scsi 7 device, it occurred to me that maybe I needed
> > to change the jumper so that the first drive is "seen" first but after
> > taking the drive out of its tray I could not see any jumper switches...
> > (plus I would not know how to change the other drive's jumpers as nothing
> > is written about it on the drive itself)
>It is better to boot from CD, then you can see the other disks just
>I will also make the 'dd' that you mention later more reliable as there
>will not be any open files on the source. There are rescue floppies that
>can do this too if you cannot boot from a CD.
> > I have also  tried to boot from the first drive and then insert the second
> > drive but I cannot find the second drive (doing something like fdisk
> > /dev/sdb, but the second drive is probably also called sda since it has its
> > own version of RH on it).
>No, the two disks will have unique names when each system is booted. You
>can look at the boot messages to see what each disk is called. It is
>critical that you absolutely know which one is the "good source" and
>which is the target that will be overwritten.
> > So, my question: how do I format the second drive and make it visible to
> > the system. And secondly while I am at it, I was going to use:
> >
> > dd if=/dev/sda of=/dev/sdb bs=1M   (I know nothing about dd but that's what
> > I have found in FAQs)
> >
> > Is this a good way of doing it, and do I need first to create identical
> > partitions on drive 2 as on drive 1, and if yes, how do I do that?
>This is fine, it will copy the partition table too (I assume the two
>are identical). Best dome when the source is unmounted, but make sure
>you /dev/sda is really the source you want to copy (mount, inspect it,
>Be careful, you can blow your data away easily when working at this low
>level. Naturally, you should take good backups before starting this
>Good luck.
>Eyal Lebedinsky (eyal at eyal.emu.id.au) <http://samba.org/eyal/>

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