2TB RAID-1 Zentyal installation fail at GRUB

[alecaru]

Please help,
I'm trying to install a Zentyal fresh install on a 2TB raid-1 configuration (Hardware)
Grub can't install in any of the /dev/mapper/xxxx partition, it gives error (can't remember the error literally).
Then the Zentyal continue to install but as expected won't boot.

I read of some problem when using Ubuntu on this particular configuration what should I try to do?
Thanks.

[jbahillo]

Hello:

First of all I would advise you to make sure that your RAID controller is fully supported by Ubuntu. Unfortunately I have seen many RAID controllers  (even some on the certified hardware from Ubuntu) which are only supported in AHCI mode (not RAID)

[robb]

Instead of trying to solve your problem with software, I would like to suggest to approach this another way:
Add a 3rd disk for / and use your Raid 1 for /home

[nubro01]

I have had simular problems when I tried to install Zentyal 3.4 beta from a usbstick. For some reason my internal system ssd was /dev/sdb and grub defaults to /dev/sda!
At install I had to change the install position, but I forgot how, because when I install from CD all goes fine.

[StuartNaylor]

Grub and /boot load before any drivers but saying this there are a few things with RAID.

Firstly when it comes to hardware RAID there are a huge amount of motherboards with RAID on-board. In most cases its what is termed as fakeraid.
Also with any hardware RAID there is one consideration that if your hardware fails you will probably have to source exactly the same hardware to ever read those disks again.
So unless you have a really top notch RAID adapter and quite a lot of spindles then I would say don't use low end hardware RAID and the difference with a few spindles doesn't have any advantage over software RAID.

The only RAID type that can be read by grub with /boot is software RAID1 a mirror or high end dedicated RAID device. So turn off your fake-raid if it is, also just a mirror might as well do it software wise.
Or on install have a small SSD or even USB for a 1GB /Boot which is big for /Boot.

Grub will install and update each spindle of the mirror. Even on RAID5 or RAID10 software arrays I keep a small partition at the end of each disk make it RAID1 and /boot and boot sectors are replicated.

Ubuntu isn't very clever when it automates the grub update and boot sectors. Practically always aims for SDA so try and get your BIOS settings right and your drive cabling.
I have a SSD Cache drive that has its own format and Ubuntu still uses that, I just unplug whilst I install.

Have a google about fakeraid and the disadvantages of hardware dependent disk reading. Software RAID like I say unless you are going for a high end, high spindle count.

https://help.ubuntu.com/community/FakeRaidHowto
http://en.wikipedia.org/wiki/RAID
 

[alecaru]

I have had simular problems when I tried to install Zentyal 3.4 beta from a usbstick. For some reason my internal system ssd was /dev/sdb and grub defaults to /dev/sda!
At install I had to change the install position, but I forgot how, because when I install from CD all goes fine.

This seems the best approach to me but I have two questions:
1) how will I cope with redundancy, if my / directory will fail (the first non-raid hdd) what do will happen, will I be able to boot /home without / ?
2) how to perform this? I'm new on grub, what are the requested steps?

[StuartNaylor]

Turn off your hardware RAID or remove. Add the two disks normally.

Zentyal install choose expert mode.

Basically allows you to partition those disks. This bit is up to you but I usually create a separate /home partition.
It can either be an all in one mounted as / or / and home or even a small boot partition.
Then go to the RAID manager section and create a RAID1 array select the partitions and accept.
The set the mount points on that RAID array and continue the install as normal.
Because its software RAID and RAID1 the install will continue as normal.
Everything will be mirrored and grub will update both disks at the end.
Also you choose to boot degraded or not.

[Video-VV]

Is not the first time I meet a situation where on a cheap hardware RAID and hardware is included when you install Ubuntu Server gets the following error

Unable to install GRUB in /dev/mapper

Performing 'grub-install' /dev/mapper 'crash.

This is a critical mistake.
In fact - it's not a bug, just the system failed to identify itself partitions on RAID-device. To continue, you need to go to the second console by pressing Ctrl + Alt + F2 and run the following command:

ls -l /dev/mapper

Which will show the marks on the device with all sections. Now we need to go back to the first console Ctrl + Alt + F1 and will prescribe for GRUB-install path:

/dev/mapper/<name-your-disk-array>

Just yesterday, put the system on a RAID array of firms nvidia and it looked like this:

/dev/mapper/nvidia_ccbeedeb