[Gllug] Problems on a box running RAID 1

[Chris Bell]

On Fri 14 Sep, Nix wrote:
> 

> 
> No no no! You'll get *awful* performance if you do that, and on most IDE
> and ATAPI systems I've seen, if one drive on a cable dies it takes the
> others out with it.
> 
   Exactly why I separated the drives in the first place. I still do not
understand why the CD/DVD does not read or write without problems, but could
use a SCSI CD if I can find one that works, and have another box that does
work perfectly (Fujitsu-Siemens P4-3.6GHz motherboard with single IDE but
four SATA, using an IDE CD/DVD and two pairs of RAID1 SATA drives).


> 
> >    Am I likely to hit any unexpected snags when I re-arrange an MD array, or
> > do I just have to reconfigure MDADM and GRUB?
> 
> Rearranging should work for RAID-1 no matter what: it's a mirror, so it
> doesn't matter what order the components are assembled in.
> 
> If you ever plan to use anything but RAID-1 and want to avoid destroying
> your data on rearrangement, *avoid* using the kernel auto-assembly
> feature, use mdadm in an initramfs or initrd to assemble the array, and
> use the DEVICE partitions stanza and uuid labelling in /etc/mdadm.conf.
> e.g. from one of my RAID installations, with three arrays (one RAID-1,
> two RAID-5):
> 
> DEVICE partitions
> ARRAY /dev/md0 UUID=3a51b74f:8a759fe7:8520304c:3adbceb1
> ARRAY /dev/md1 UUID=a5a6cad4:2c7fdc07:88a409b9:192ed3bf
> ARRAY /dev/md2 UUID=fe44916d:a1098576:8007fb81:2ee33b5a
> 
> MAILADDR postmaster at esperi.org.uk
> 
> If you name by uuid like this, the array will always be assembled in the
> right order, no matter what happens to the underlying physical devices'
> names, device discovery ordering, and so on.
> 
   Thanks for the info, and it more or less confirms my thoughts about
RAID-1. The drives are set up using mdadm in Debian Etch.

Microsoft sells you Windows ... Linux gives you the whole house.

-- 
Chris Bell

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