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software raid: I must be stupid...

glideFX

glideFX

Member
...because I'm not able to install a simple Ubuntu server on a software RAID 10.

I always get the message

Code: 
Unable to install GRUB in /dev/sda
Executing `grub-install /dev/sda` failed.
This is a fatal error.

I have 4 WD RED 3TB configured this way

Code: 
RAID 10 
4.0 GB swap
5.9 TB /

disk 1
2 GB raid 
3 TB raid 

disk 2
2 GB raid
3 TB raid

disk 3
2 GB raid 
3 TB raid 

disk 4
2 GB raid 
3 TB raid


I also tried to create a third partition (/boot) but seems to be ignored
Another strange thing: I'm unable to select the 'bootable' flag when I create the partition (I mean the raid member partition)

Also tried disabling all the stuff about safe boot and uefi in the bios...

The mainboard is an ASUS P8Z77-V LX


what's wrong? :'(
 
Last edited:
Do a checksum of your downloaded ISO.
Not beeing able to make another partition should make you worry.
Try and make the installation on a spare disk to see if everything installs correctly, and if you can create more partitions and set the bootable flag.
 
glideFX said:
good point, I think this is the problem.
will try a test install on a single disk to be completely sure...

at this point what I can do? something with the intel fake raid?
I will go for a 5th disk or dedicated raid controller only as last solution..

thank you
Click to expand...

From the link it sounds like what you want to do is create 2 RAID volumes.

1 small one ~500MB should be enough that is a RAID1, with only 2 disks, which is bootable.

and a second one using all 4 disks that uses the remainder of the space for your RAID10.
 
Those are 3TB drives, so I presume that the partitioning has to be GPT. I would try UEFI boot with GPT.

RAID1 mirrors two partitions.
When using traditional MS-DOS partition table you would write stage1 of GRUB (legacy GRUB, not sure about your GRUB2) into MBR of one disk and make it point to stage2 in /boot partition on that (or the other) disk. You would write the stage1 to the MBR of the other disk too. MBR is not mirrored by software RAID (except perhaps in partitionable RAID mode).

Boot is read-only, so it won't corrupt the RAID1 array, even though it accesses only one disk. (Legacy) GRUB cannot tell a difference between a partition that starts with filesystem and a partition that starts with filesystem but is actually part of RAID1. Some RAID1 versions place RAID metadata into the beginning of the partition and that would break boot.

The GRUB2 might/does support more things though.


UEFI places "grub.efi" and "grub.conf" into EFI System Partition, not to MBR (because GPT does not have MBR). The EFI partition (a FAT32) is mounted as /boot/EFI. The /boot may or may not have to be separate partition from /, depending on what the EFI version of GRUB supports, i.e. where it can read the kernel from.

tldr; GPT partitioning. Small (100MB) EFI partition into two disks. Max 500MB /boot to two disks. The rest probably for the RAID-10.
 
mv2devnull said:
Those are 3TB drives, so I presume that the partitioning has to be GPT. I would try UEFI boot with GPT.

RAID1 mirrors two partitions.
When using traditional MS-DOS partition table you would write stage1 of GRUB (legacy GRUB, not sure about your GRUB2) into MBR of one disk and make it point to stage2 in /boot partition on that (or the other) disk. You would write the stage1 to the MBR of the other disk too. MBR is not mirrored by software RAID (except perhaps in partitionable RAID mode).

Boot is read-only, so it won't corrupt the RAID1 array, even though it accesses only one disk. (Legacy) GRUB cannot tell a difference between a partition that starts with filesystem and a partition that starts with filesystem but is actually part of RAID1. Some RAID1 versions place RAID metadata into the beginning of the partition and that would break boot.

The GRUB2 might/does support more things though.


UEFI places "grub.efi" and "grub.conf" into EFI System Partition, not to MBR (because GPT does not have MBR). The EFI partition (a FAT32) is mounted as /boot/EFI. The /boot may or may not have to be separate partition from /, depending on what the EFI version of GRUB supports, i.e. where it can read the kernel from.

tldr; GPT partitioning. Small (100MB) EFI partition into two disks. Max 500MB /boot to two disks. The rest probably for the RAID-10.
Click to expand...

the installation worked this time, but after the reboot it was unable to boot correctly and started the grub rescue with the "error unknown filesystem" error.
typing 'ls' I had no "msdos" partitions, they were all gpt.
no way to ls into one of them like suggested googling the problem.

gave up on raid for the boot, installed a 5th drive for /efi /boot / and created a raid 10 ( /srv ) on the four 3TB drives.

learned a bit about software raid and wasted a lot of time.
thanks to all for the support


bye
 
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