RAID10 not working in install

Bill Davidsen davidsen at
Sat Feb 23 21:55:58 UTC 2008

Bruno Wolff III wrote:
> On Fri, Feb 22, 2008 at 19:38:14 -0500,
>   Bill Davidsen <davidsen at> wrote:
>> I was doing a new install (reinstall) of FC8 Unity and when I tried to 
>> configure the disks and partitions I put a software RAID partition on 
>> one drive, and another of the same size on the other drive, and then 
>> told the installer to make them RAID10. I got back a message that at 
>> least four drives are needed for RAID10.
> The installer doesn't let you use all of the modes that mdadm can. It is
> sort of a nanny to keep people from picking unusual combinations that
> they may not really want.
> I have asked for raid 1 to work with 1 element in anaconda several times (as
> this makes adding elements later a lot easier). I think the current status
> is that it will use a preexisting raid 1 array with one element (not a
> 2 element array with one element failed), but not allow you to create one.
I can see being reluctant to allow creation of an array with failed 
elements, but RAID10 with two drives is not in any sense a degraded 
array, it a fully functional configuration. RAID1+0 (stripe over mirror) 
is a totally different configuration, and does require at least four 
members and the number must be even. RAID10 requires two or more, three 
is a perfectly valid number.

I can see not supporting degraded configurations, but the RAID10 is just 
a think-o AFAIK, someone made an install menu and didn't know what it 
really meant. I see that the rescue disk doesn't assemble and use RAID10 
swap, either, although you can do it by hand.

Hopefully this will get fixed for FC9!

Bill Davidsen <davidsen at>
  "Woe unto the statesman who makes war without a reason that will still
  be valid when the war is over..." Otto von Bismark 

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