I'm new to unRAID and managed to get an array up and running after reading the instruction supported by all you  wonderful folks. The problem I am running into, is when I replaced my motherboard and added a new hard drive. I had unRAID BASIC running on an old Dell computer, and with space running out, and adequately satisfied decided to upgrade to unraid Pro. In order to support more hard drives, I also replaced the motherboard with an Asrock 880GM LE FX, which comes with 6 x 3 GB/s SATA ports.

 

After I built the new array and booted back up, everything went beautifully (again, thanks to the great instructions!). My only problem is that the new array is registering my brand new Seagate Barracuda Green 2 TB hard drives (ST2000DL003-9VT166) as IDE devices, assigning them /dev/hdX.  I added another older Samsung Harddrive, and that was recognized as SCSI (/dev/sdX)

 

My problem, I guess is that I don't very well understand the difference between IDE and SCSI. From what I can gather, these were ways that the motherboard uses to communicate the hard drive's electronics, right? for unraid at least, I read that SCSI was almost always preferred over IDE especially for newer hard drives. So why is my new motherboard emulating my brand new hard drives as IDE? When the system booted up, I checked the BIOS and set the SATA setup to "Emulated AHCI" (options were IDE/AHCI/RAID). But this still did not fix the issue.

 

I don't personally care one way or the other, but I did notice that during preclear, the IDE emulated drives were running at suprisingly slower speeds than the ones recognized by unRAID as SCSI devices.

 

Can someone please explain to me what I am doing wrong? Or have I got this all wrong? Is IDE and SCSI a function of the motherboard, or is it something unique to the hard drive? How can I get the best performance out of my array? Any help would be greatly appreciated.

 

Thanks!

 

 

Ras

All drives should be detected as SATA using AHCI. This is a motherboard setting.

All drives should be detected as SATA using AHCI. This is a motherboard setting.

Many motherboards have multiple settings for how the disks are "emulated" as IDE.  You want AHCI enabled for all ports. 

(The IDE emulation is because windows XP and prior have NO SATA drivers.  If the emulation did not exist, those OS could not be booted)

 

Look further for how to enable AHCI on your MB in your BIOS.  (There may be two places, one for some of the ports on your MB, the other for the remaining)

 

As you've seen, the IDE emulation mode is frequently much slower.

All drives should be detected as SATA using AHCI. This is a motherboard setting.

Many motherboards have multiple settings for how the disks are "emulated" as IDE.  You want AHCI enabled for all ports. 

(The IDE emulation is because windows XP and prior have NO SATA drivers.  If the emulation did not exist, those OS could not be booted)

 

Look further for how to enable AHCI on your MB in your BIOS.  (There may be two places, one for some of the ports on your MB, the other for the remaining)

 

As you've seen, the IDE emulation mode is frequently much slower.

 

Is there any affect on your disk assignments/shares/data with unRAID if you have it setup in IDE mode and you just switch it to AHCI? I know doing this with a PC running an older OS (XP for instance) will not boot if you change this mode. You usually need to do a boot repair of some kind.

Thanks so much, guys --- I finally figured out this problem.

 

After doing quite a bit of digging, I found that my BIOS has an option called "Combined SATA IDE mode" which was set to [ENABLED] by default. This mode, forced IDE emulation for SATA ports 5 and 6, so that I ended up getting four of my six ports in AHCI and two ports (SATA-5 and SATA-6 in IDE mode), which are the ports to which these drives were connected to. As soon as I disabled that option, and rebooted, voila! -- All six of my drives are now recognized as AHCI.

 

I cannot imagine why such a new motherboard would have such a useless option (maybe to facilitate IDE operation for older OS, is all I can think of), but either way the problem is now solved.

 

Thanks again everyone!

 

I cannot imagine why such a new motherboard would have such a useless option (maybe to facilitate IDE operation for older OS, is all I can think of), but either way the problem is now solved.

 

Thanks again everyone!

Windows XP and all Windows OS prior have no SATA drivers.  If the motherboards did not have the emulated IDE mode, Windows XP (and prior) could not boot because they only can boot from an IDE drive.