Linux software RAID 10 implementation

I don't want to force anybody to make it on behalf of me but trust me: i've looked hundreds of sites and i can't find a good starting point for this.

I have 4x500Gb HDD's which i want to set up in RAID 10. The most promising description is here, but it's a little old and unclear for me, above all i prefer Debian over Ubuntu (i know there are slight or no differences).

Is it possible to build RAID 10 with Debian's installer or i need to build RAID 1 first in the installer then use mdadm later?

What is the best practice for building software RAID 10 under Linux (Debian)?

Thanks for your time, fabrik

I believe RAID10 support (through the fancy all-in-one RAID10 driver rather than doing a RAID0 of RAID1s) is not present in the installer for Etch or Lenny, but it has been added for the current development version so will be in the next release (or available now if you don't mind using the testing distribution, but this is not recommended in a production environment).

For now you should be able to construct RAID10 arrays in the installer the traditional way, i.e. a nested RAID arrangement, by creating a pair of RAID1 arrays and then adding them into a RAID0 array - though you obviously won't get the all-in-one RAID10 driver's extras (3 device array support, arrangements that can improve read speed for some I/O patterns, and so on) this way.

IIRC this is the same for Ubuntu's alternate installer (the standard installer doesn't offer RAID options at all). I only remember seeing 0, 1, and 5 as options when I installed 9.10 into RAID arrays on my netbook.

In any case you need to make sure that your /boot filesystem is not on RAID10 (or anything other then RAID1 or a plain volume for that matter) as Grub can not boot off RAID other then RAID1. You should be OK to have your root filesystem on RAID10 though.

Linux Kernel RAID10 module is EXPERIMENTAL! I lost whole data on a server because of this. (status EXPERIMENTAL still exist in 2.6.33.2)