Miguel Medalha wrote:
> Yet, maybe I am being stupid but it seems to me that there still is
> something to my original question...
>
> Under hardware RAID, a dedicated processor on the RAID controller does
> all the job of RAID calculations.
> Under software RAID, as you said, "you create partitions on the disk,
> then combine them into md devices".
>
> Isn't there any space for something in which the disks are made parts of
> RAID arrays *before* the partitions are created and yet all the RAID
> operations would be made by the main CPU and so it would still be
> considered software RAID? What would happen if the equivalent of mdadm
> was *included* in the OS kernel?
I'm not sure it would be possible to boot such a drive. Hardware raid
has the benefit of a bios that understands it at boot time. Software
raid1 only works for /boot because each of the mirrored partitions looks
just like a normal one to bios and grub. For non-boot drives you can
get the same effect (and more) by putting the whole drive in one
partition, combining those with raid, then running lvm on top of that.
--
Les Mikesell
lesmikesell at gmail.com