mdadm issue

[lists at ralii.com]

> 
> From: Luc MAIGNAN <luc.maignan at winxpert.com>
> Date: 2006/01/24 Tue PM 12:13:15 EST
> To: For users of Fedora Core releases <fedora-list at redhat.com>
> Subject: mdadm issue
> 
> Hi,
> 
> Is there a way to setup a RAID5 feature on the whole main disk (I mean
> even the disk on which the / is) ? When I try this, I have the error
> "device busy". So isn't possible to mirror the whole system ?
> 
> Best regards
>

Several issues with your question....

1) RAID implies multiple devices.  Do you have more than one hard drive?  RAID-5 implies at least 3 drives....

2) You cannot reverse gears.  If you want to put "/" on a RAID device, you generally need to do it at installation time, or plan to do it in a recovery mode ("rescue mode") and expect to have to "backup-create array-restore" as a process.

3) You cannot put /boot on a "striped" array.  You can put /boot on a RAID-1 array, but there are implied MBR issues that you would need to be aware of.  There are HOWTO articles on the web to help you with dealing with it.

4) In general, mdadm seems to intend to use partitions as the members of the array, not "whole disks", though perhaps it is possible.  In general, for RAID'ing whole disks, you should look at a hardware RAID controller, rather than software RAID (also solves #3).

--Rob