Our HP Proliant ML150 is configured as RAID in the BIOS, and created a "Logical drive" (using two 250GB HD) as RAID 1+0.
The procedure seems to be Ok.
However, when installing the OS (Ubuntu 10.10) the partitioner utility still shows our two HD
/dev/sda
/dev/sdb
I was expecting to see only one drive, since the two HD are RAIDed.
Is there a special step missing (checked again at boot, the RAID logical drive is still alive)?
edit It seems Ubuntu does not recognize the logical RAID drive.
edit2 RAID 1+0 is possible with two disks. See this Wikipedia page.
RAID 1+0: mirrored sets in a striped set (minimum two disks but more commonly four disks to take advantage of speed benefits; even number of disks)
Either get a hardware RAID controller like a SmartArray P4xx or use software RAID. SW RAID works well on Linux - much better than Windows - so you may not need HW RAID.
The main advantage of HW RAID is battery backup which gives you a fairly good chance of surviving a power outage without corrupting your disk. You might find it worth your while to get a HW RAID controller for this reason.
Ubuntu doesn't recognise the RAID logical drive created by the BIOS.
And no driver is available.
So our choices are down to
It is impossible to implement fully functional RAID 0+1 using only 2 hard drives (refer to the RAID guides, for example here http://www.bjorn3d.com/read.php?cID=886). It is pointless to use RAID 0 without getting any advantage in speed and capacity, also using RAID 0 is no option for the server, because if one disk fails - you loose all the data you have. So there is few options: