What is 'AHCI mode' - HP ProLiant MicroServer Gen8

Question

I have just purchased this server and I would like to install Ubuntu Server on it. I would like to keep RAID support, although I'm currently only using one HDD which will have my files and OS on it.

I've seen I can install Ubuntu after I set the embedded SATA configuration to 'AHCI mode'. What does this mean? What are the pros and cons?

Does this turn off RAID? I mainly bought this because eventually I'd like to have two drives mirroring each other. I've also read somewhere on ask ubuntu that going in to 'AHCI mode' mode makes the fans louder too.

I've also just seen this if it helps:

NOTE: The B140i storage controller (HPDSA) driver v1.2.4-140 is ONLY supported with Ubuntu 14.04.1 LTS (v3.13.x) kernel. Please use AHCI Mode with newer Hardware Enabled Kernels (HWE). Future platforms with the Dynamic RAID controller will be certified using AHCI SATA mode.

This is the first server I've ever owned so any help setting this up will be much appreciated.

EDIT: I've also seen this, will using this custom version of Ubuntu allow me to install it whilst keeping the smart array? Heck what even is smart array?

Solution

AHCI is the standard interface for SATA controllers. Other options usually include IDE mode, where the controller pretends to be an old IDE controller for compatibility with older operating systems, and RAID, which means fake raid support. Fake raid is actually just an AHCI controller that has bios code and windows drivers to implement raid in software. For more information, see http://wiki.ubuntu.com/FakeRaidHowto. Unless you are dual booting with Windows, it is best avoided and you should stick with conventional linux software raid, which is better supported.

Comments

[David Foerster]

If you want to use a RAID for your Linux system, the software RAID solution(s) inside the Linux kernel and its user-space utilities are usually far superior to on-board RAID solutions.