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How to install Ubuntu on SSD in ODD bay with AHCI


BlueThing
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Hello everybody,

yet another Gen8 newbe in the forum :)

I'd like to install an Ubuntu Server on a 2.5" SSD in the ODD bay.

Since I'm still debating, whether to use the AHCI vs B210i controller I've decided to try both type of installations.
Using the B210i I could easily define the ODD drive as a RAID-0 array and install and boot Ubunto on/from it.
Yet, when I tried to use the ACHI mode, I could not identify the ODD drive for the installation.

1) Just to make sure that I've used the correct setting in the BIOS.

     Could someone please advice how exactly one change between AHCI and B210i mode in the BIOS?

2) Does anybody know any step by step tutorial for installing Ubuntu in AHCI mode?

    (I could only find this tutorial for B210i mode: http://homeservershow.com/forums/index.php?/topic/8426-installing-ubuntu-to-ssd-in-odd-bay-with-b120i-raid-1/?hl=ubuntu)


apreciate any thoughts you might have

BlueThing

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Have a good browse through the forum there's lots of information on this issue.

 

When the controller is in AHCI mode it's not possible to boot from the ODD drive if other main bay drives are present. There is a work around but it requires a USB/SD drive inserted in one of the internal ports as well as the SSD drive. The idea is to boot from the USB/SD drive and then load the OS from the SSD. This is documented somewhere in full but I don't have access to the link but from memory.

 

Remove all the main drives.

Install SSD and USB/SD card.

Install Linux OS (Ubuntu in your case) on the SSD.

When it gets to the question about where to install grub pick the USB/SD card rather than the SSD.

Once complete reboot and check everything is OK.

Insert main drives and it should still boot.

 

It's worth hunting out the proper instructions though as the above is just an idea of how to do it not a step by step guaranteed to work list.

 

Richard

 

 

This is not the guide I remember but may help.

 

http://jarrodla.blogspot.co.uk/2014/04/hp-microserver-gen8-boot-from-5th-sata.html

Edited by RichardG
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Just to make sure of what I'm seeing here on my Ubuntu install.

 

I've setup the SSD on port 5 (ODD) as a Raid 1 array on its own. I can boot from this drive using a standard Ubuntu install, with all the other bays full.

 

Issuing the command dmesg | grip -I ahci reveals

 

scsi0 : ahci

scsi1 : ahci

scsi2 : ahci

scsi3 : ahci

scsi4 : ahci

scsi5 : ahci

 

So I'm thinking that even running in this weird 1 disk raid mode, it's using AHCI feature anyway. Would this be right?

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Are you sure it's RAID 1 and not RAID 0.

 

When i used only a single drive to set up an array i only had the option of RAID 0. Which also make sense to me since you can't mirror a disk using only one disk.

 

In any case I've chosen at the end to use pure AHCI mode (with the USB grub workaround).

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I think you're right (it's Raid 0). I couldn't remember how I set it up.

 

Any reason you're choosing the pure AHCI mode over the Raid Mode? Seems like a heap of work for no benefit (that I can see, happy to be proven wrong)

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First I'd like to use the opportunity to thank RichardG for the answer. Finally I have my system up and running the way I want it.

 

@demomanca
to my understanding those are the pros and cons of AHCI vs B120i

 

Controller

AHCI

B120i

B120i

My Requirement

Array configuration

n/a

Singe drive

(RAID 0)

Multi drive

(RAID 0,1 or 10)

No special need for redundancy.
I only need backups.

Fan noise

Reported to be loud.
I find it the same

 

Quiet

Quiet

Server in the living room.

ODD Install

Bays 1-4 must be removed during installation

YES

YES

Ubuntu on 2.5" SDD in ODD drive

ODD Boot

No. But…

Workaround with USB

YES

YES

Ubuntu on 2.5" SDD in ODD drive

Hardware
Interchangeability

YES

Maybe.
No guarantee

NO

In case of server replacement (due to HW failure or future upgrade) I don't want to be bound to specific hardware.

Kernel Drivers

Not required

Don't know

Required

better not so I can update kernel without worrying



At first I've decided to go for the same approach as yours: B120i with single drive arrays (of RAID 0) configuration.
I've chose it due to the somehow simplified installation and boot process and the reduced fan noise level.


However after installation I've encountered issues to format my HDD in bay 1 using mkfs (I got a hardware interrupt/failure message and system halt).  I'm not sure if my hpvsa driver was not properly installed, but after the 3rd try , I've decided to change my mode of operation to AHCI and reinstall the system.


In my personal opinion, I don't find a noticeable noise level difference between the two modes. In any case, I find the noise level acceptable for my living room (as long as I don't have to sleep there).

Personally I do find the interchangeability with other hardware important, and I'm also a bit more relaxed that I'm not dependent on kernel drivers if I will have to do some updates in the future.

In case you'd like to change your configuration to AHCI please note that I also had a small issue with the USB boot workaround:

I've installed the USB flash in the on-board USB port. By doing so, my keyboard became inactive. I think the server has some security feature, forcing the BIOS to disable the external USB port automatically.
To over come this, first I had to shutdown my system with the help of the iLO remote console (another option is brutally turn of the power but I took to opportunity and challenge to find out how the remote console works). Then I pluged a keyboard directly to the on-board USB port. Logged to the BIOS (F9) and re-enabled the external USB ports.

I admit that I had some adventures until I got the server setup the way I want it, but you can imagine my joy now that everything is working fine :)

 

And now the same question to you. Why you chose B120i single drive mode? :)

 

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Fair enough.

 

Main reasons I went with the "Raid0" 1 drive config:

  • Previous posts seem to indicate that if you have at least 1 array configured, the fans spin slower, although I believe this is fixed
  • Having that 1 array configured allowed Ubuntu setup to see the disk, and also allowed me to select it to boot from. No issues during installation at all.
  • Previous posts here indicate that even if you have the 1 drive setup as a raid 0 array, the controller and OS just treat it like a single disk, to the point that you can remove it and read it from another computer without a b120i controller <- this was a big one for me
  • I didn't have any issues with the other drive bays (eg, getting them setup etc, however I didn't use mkfs, I used ZFS)
  • Large scripts manually installed to USB drives scare me :)

I still have some concerns about my particular setup, namely finding a definative answer to if Ubuntu is using AHCI features on my SSD, namely NCQ. Given I can read temp sensors, and from what I can gather AHCI has been enabled (across all 5 ports) I think it is, but I'm not 100% on this. It seems to run fine, and hdparm benchmarks are good (hdparm -t /dev/sde gives 296.16MB/s, hdparm -T /dev/sde gives 5005.17MB/s).

 

What I'm hoping is that the way I've configured this doesn't bite me in the ass down the track.

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