[CentOS] setting up CentOS 5 with Raid10

[Ruslan Sivak]

Les Mikesell wrote:
> Ruslan Sivak wrote:
>> B.J. McClure wrote:
>>>
>>>> I would like to set up CentOS on 4 SATA hard drives that I would 
>>>> like to
>>>> configure in RAID10.  I read somewhere that Raid10 support is in the
>>>> latest kernel, but I can't seem to get anaconda to let me create 
>>>> it.  I
>>>> only see raid 0, 1, 5, and 6.
>>>>
>>>> Even when I tried to set up raid5 or raid1, it would not let me put 
>>>> the
>>>> /boot partition on it, and I though that this was now possible.
>>>>
>>>> Is it possible for me to set up the configuration I'm looking for?
>>>>
>>>> Russ
>>>>
>>> Cannot speak to raid 10 but have been running 4.4 an 5.0 with raid 1 
>>> and /boot partition on md0 for some time.  Have not seen the issue 
>>> you refer to.
>>>
>>> bj
>>>
>>>
>>
>> Well as far as Raid10, it's not even an option for the installer.  If 
>> I do select raid1 for the entire array, I only get the space of 3 of 
>> the 4 drives, and the installer still complains that I cannot put 
>> boot on a raid system.
>> Is there a how-to somewhere on getting this to work?
>
> I don't know if the installer will let you do it, but you are supposed 
> to be able to create RAID1 devices, then stripe across them by using 
> those md devices in a RAID0.  I'm not sure if there is any advantage 
> to that over using LVM to combine the RAID1 devices though.  
> Personally I prefer to use RAID1 and deal with the space on separate 
> mounted partitions since it permits recovering the data from any 
> single drive but if I had to have a larger chunk I'd probably put 
> /boot on a RAID1 and the rest in mirrored partitions combined in LVM.

I just did an install where i set up boot on raid1 (sda1,sdb1 with sdc1 
and sdd1 as spares), swap on raid0 (sda2, sdb2, sdc2, sdd2) and then 
created 2 LVM partitions /dev/md2 (raid1 of sda3 and sdb3) and /dev/md3 
(raid1 of sdc3 and sdd3).  I then combine the 2 partitions in LVM and 
put root on it. 

Everything installed fine, but got stuck at the grub prompt. 

I am now trying to set up raid10 manually by using mdadm, but it gives 
me an error, and when looking at dmesg, it says "md: personality for 
level 10 is not loaded!". 

Does this mean that the currently compiled in kernel doesn't support 
raid10? 

Russ