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Old 11-27-2009, 09:32 PM
Dan Cowsill
 
Default Migrating RAID: Degraded RAID5 from RAID1?

Hello list,

Currently I have two terabyte hard disks in a RAID1 configuration
using software RAID. What I'd like to do is add a third disk and
arrive at the end with a RAID5 array. The problem is I have limited
disk space and not enough room to back up all of the data on the array
in its current form. What I'd like to know is if it is possible to
use two disks to make a degraded RAID5 array, move the data onto it
from one of the mirror disks, and then add the mirrored disk into the
new array?

Thanks,
D
 
Old 11-28-2009, 06:30 AM
andrey larin
 
Default Migrating RAID: Degraded RAID5 from RAID1?

let suppose
sda and sdb is raid 1 md1and new sdcremove sdb from raid*mdadm /dev/md1 -f /dev/sdbmdadm /dev/md1 -r /dev/sdbthen create degraded raid 5
don't forget md1 is still runningmdadm --create /dev/md2 --level 5 -n 3 /dev/sdb /dev/sdc missingthen copy all data from md1 *to md2fix /etc/fstab and /boot/grub/grub.conf
destroy md1*and add sda to md2

2009/11/28 Dan Cowsill <danthehat@gmail.com>

Hello list,



Currently I have two terabyte hard disks in a RAID1 configuration

using software RAID. *What I'd like to do is add a third disk and

arrive at the end with a RAID5 array. *The problem is I have limited

disk space and not enough room to back up all of the data on the array

in its current form. *What I'd like to know is if it is possible to

use two disks to make a degraded RAID5 array, move the data onto it

from one of the mirror disks, and then add the mirrored disk into the

new array?



Thanks,

D





--
Ларин Андрей

тел 89093090949
 
Old 11-29-2009, 01:28 PM
Dan Cowsill
 
Default Migrating RAID: Degraded RAID5 from RAID1?

On Sat, Nov 28, 2009 at 2:30 AM, andrey larin <ubergitler@yandex.ru> wrote:
> let suppose
> sda and sdb is raid 1 md1
> and new sdc
> remove sdb from raid
> mdadm /dev/md1 -f /dev/sdb
> mdadm /dev/md1 -r /dev/sdb
> then create degraded raid 5
> don't forget md1 is still running
> mdadm --create /dev/md2 --level 5 -n 3 /dev/sdb /dev/sdc missing
> then copy all data from md1 *to md2
> fix /etc/fstab and /boot/grub/grub.conf
> destroy md1
> and add sda to md2

Excellent. All I need to know is that there is indeed a mechanism for
doing this and that I am not crazy. Man pages should fill in the
rest.

Thanks for your help, Andrey
 
Old 11-29-2009, 02:32 PM
Volker Armin Hemmann
 
Default Migrating RAID: Degraded RAID5 from RAID1?

On Freitag 27 November 2009, Dan Cowsill wrote:
> Hello list,
>
> Currently I have two terabyte hard disks in a RAID1 configuration
> using software RAID. What I'd like to do is add a third disk and
> arrive at the end with a RAID5 array. The problem is I have limited
> disk space and not enough room to back up all of the data on the array
> in its current form. What I'd like to know is if it is possible to
> use two disks to make a degraded RAID5 array, move the data onto it
> from one of the mirror disks, and then add the mirrored disk into the
> new array?
>
> Thanks,
> D
>

easy, have a look at 'grow'. Oh and use google. There are a lot of examples
how to go from raid1 to raid5. It is easy. No disk pulling is needed.
 

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