[CentOS] RAID 1 Post Install

Hal Martin hal.martin at gmail.com
Thu Dec 18 01:42:53 UTC 2008

Just along these lines, would it be possible for me to break RAID 1 on
the two internal drives into RAID 0 and then mirror that new RAID 0
array onto a SATA drive using RAID 1 without loosing any data?

I used JFS as the file system for the RAID 1 array, so that may have to
be changed to XFS as you cannot dynamically expand JFS to the best of my


Kai Schaetzl wrote:
> Tom Brown wrote on Tue, 02 Dec 2008 17:29:06 +0000:
>> http://tldp.org/HOWTO/Software-RAID-HOWTO-5.html
> unfortunately that and the mini-howto are both very much outdated. Many of 
> the stuff it mentions (like mkraid, /etc/raidtab) is not part of the 
> distro anymore. You use mdadm nowadays. Those parts that contain mdadm 
> commands are still valid.
> Does this "Silicon Image SATA controller" not include Hardware RAID by 
> chance? 
> The basic steps for software-RAID are:
> - decide about the partitions the RAID devices will be based on
> - if it is used only for data you may probably want to have just one RAID 
> partition:
> mdadm --create /dev/md0 --level=1 --raid-devices=2 /dev/sda /dev/sdb
> (I assume you can use sda and sdb. I always use several RAID partitions, 
> so I never used the whole disk.)
> put LVM on it:
>   pvcreate /dev/md0
>   vgcreate myvolumegroupname /dev/md0
>   - creates vg myvolumegroupname on it
> - start adding your logical volumes:
>   lvcreate -L50G --name myname myvolumegroupname
>   - adds a 50G logical volume named myname
>   - format that lv:
>     mkfs.ext3 /dev/myvolumegroupname/myname
> - copy any data you like from the old drives
> - add the mount points to fstab
> - if you don't boot from the RAID partition you are done now
> Kai

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