[CentOS] Installing on partitionable RAID arrays

Thu Mar 26 13:16:44 UTC 2009
Phil Schaffner <Philip.R.Schaffner at NASA.gov>

RedShift wrote:
> RedShift wrote:
>> Hello
>> Since linux 2.6, the md layer has a feature called partitionable 
>> arrays. So instead of having two disks, creating an identical 
>> partition table on both and then putting those partitions in RAID 1, 
>> you take those two disks and put them in one partitionable RAID 1 
>> array (in mdadm terms, "mdp") and create a partition table on the new 
>> RAID device. The advantages are quite clear compared to the old 
>> non-partitionable arrays.
>> My question is, is this supported by CentOS? The GTK installer doesn't 
>> provide a way to create such an mdp device and the integrated 
>> partitioning tool does not see for example md_d0 when I create it 
>> manually from the console.

I expect we may have to wait on upstream to have installer support. 
Anybody with RHEL want to put in an official request?

>> Another way to get CentOS on such a configuration would be to do 
>> everything manually, thus installing the base system by creating the 
>> necessary disk allocations and then rpm -i all the required packages 
>> to get it to boot. (I've done this before, it's not a big deal, you 
>> just need to follow a certain order - I remember documenting it 
>> somewhere but forgot). But since this method is probably not 
>> officially documented anywhere or even supported I'll most likely 
>> won't get any support if this setup were to fail somehow (like when 
>> upgrading between minor versions).
>> I've tried STFW'ing, but searching for centos and partitionable arrays 
>> is too ambiguous.

I tried googling too, and came up with lots of docs on "partitionable 
arrays", but nothing on installing.  Can't say for sure without testing, 
but I suspect GRUB would choke on this.  Would probably still need at 
least a /boot on a separate partition, or a standard RAID1.

>> Thanks,
>> Best regards,
>> Glenn Matthys 
> As a follow-up, I found the documentation I wrote how to install CentOS 
> without any installer:
> # First, setup your disks to your liking. You can use whatever you want 
> here,
... snip ...
> (PS: I've also attached the documentation as install_centos.txt, but 
> mailman will probably strip it)

Attachment came through fine for me.  Very interesting - might make a 
nice Wiki article, and could be included on a LiveCD as a way of 
bootstrapping a CentOS install.