[Solved] RAID1 volume size a lot smaller than it should be (Sabertooth x79).

[Premudriy]

Hello everybody,

I recently bought Sabertooth x79 and trying to setup RAID1 with 3TB drives on it to run Linux server. Here are the pertinent specs and info:

CPU: i7 3930k
Mobo: Sabertooth x79
HDD: 2x 3TB drives
BIOS: v4210 (latest)
Drives connected to: 6GB/s Intel SATA ports (SATA6G_1/2)
Intel oprom version: 3.7.0.1049

Trying to achieve: Seeing full 3TB (well, 2.5+) RAID1 volume in Linux.
What actually happens: The RAID1 volume shows up as /dev/mapper_blah, but it is only 600GB in size.


More info: The size of RAID1 shows up as 2.5TB in OPROM, which is correct. When I boot gParted or Debian they see /dev/mapper_blah partition of only about 600GB. I can't get the RAID1 volume in linux to show up with size any close to what it should be.

I tried to re-initialize the drives as GPT in AHCI mode before switching to RAID mode. Tried reset the discs to non-RAID in oprom utility and delete/recreate RAID1. Nothing seems to make RAID1 volume to display the correct size in Linux.

I really hope this is not some limitation of this board vs Linux and that there's a way to make it work.

Please help

[Premudriy]

Alright, I did a bit more reading. Seems like people recommend to use the native linux raid (via mdadm) and not use the RST/bios raid because it's flaky and mostly needed when running windows + linux. Since I'll be running only linux on it, mdadm is a better choice. The speed/cpu use difference seems to be negligible (if not better for mdadm vs dmraid) according to reports.

So I switched to AHCI again, installed xen and it's running perfectly. Also here are some links that helped me to make the choice:
http://askubuntu.com/questions/127182/installer-only-recognizes-801gb-of-a-3tb-raid1-array
http://ubuntuforums.org/showthread.php?t=1884515
http://ubuntuforums.org/showthread.php?p=11477517

[HiVizMan]

Thank you for posting back a fix and the explanation. Many folks will be helped because of this I am sure.

repped you mate