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I'm installing a few new Ubuntu Server 12.04 LTS servers, and they have two 512 GB SSDs. I want them to use software RAID 1 mirroring, so I was following this document religiously step by step:

https://help.ubuntu.com/12.04/serverguide/advanced-installation.html

To summarize the above official documentation:

to set up a software RAID 1 mirror in Ubuntu Server, you choose manual partitioning during the setup, and do this on each drive:

  • "swap" partition of roughly RAM size
  • "physical volume for RAID" partition for remaining drive size

After that, you set up the RAID 1 mirror using the RAID partitions on drive A and B, make it ext4 and containing the root filesystem partition.

Setup continues from there just fine.

One caveat: I was completely unable to select the "physical volume for RAID" as bootable. When I tried to do that in setup, it had no effect: I could press enter on the "make bootable" option all day long and nothing would ever change.

However, after install successfully completes, I have a big problem: the system won't boot! I get

Reboot and Select proper boot device
or Insert Boot Media in selected Boot device and press a key

What did I do wrong? Why can't I mark that "physical volume for RAID" partition bootable during Ubuntu Server setup? Is there some way for me to make the physical volumes for RAID bootable after the fact, perhaps from a live CD or something?

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Here goes the bug report with regards to the documentation. And, the bug report about debian-installer. – jokerdino♦ Nov 11 '12 at 11:54
And since this is a bug, we would probably close this question as off-topic. Sorry about that. :-) – jokerdino♦ Nov 11 '12 at 11:58
I guess, but see my answer. If you want something that works, I have it. – Jeff Atwood♦ Nov 11 '12 at 12:02
I'll see if I can get the Ubuntu docs team to update the documentation. And +1'ed the answer. – jokerdino♦ Nov 11 '12 at 12:08
Not sure I follow your question here. If Grub is installed to the MBR then the boot flags simply shouldn't matter at all. – Zoredache Nov 16 '12 at 2:52

1 Answer

up vote 9 down vote

Well, I was able to proceed by deviating from the official install docs slightly.

Rather than manually configuring the free space on the two drives, I selected "automatically partition the free space" on each drive.

Note that this caused automatic creation of a 32 GB (equal to RAM size) swap partition, and one large ext4 partition. I changed the ext4 partition to RAID, then I was able to mark it bootable at last!

Ubuntu RAID 1 config

Note the little "B" next to the RAID partition on the first sda drive.

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Alternatively you could boot from a CD and configure grub manually, but that's a little too involved to sum up in an answer. Too bad about the waste of disk space though. – wds Nov 11 '12 at 12:12
@wds "too involved to sum up in an answer" What hath Ubuntu wrought? – jscott Nov 11 '12 at 23:56
did you find a way to fix a system that already tried to boot and failed? I already spent a bunch of time setting one up and it'd suck to do it again :/ I guess I would have to boot off the livecd again, mount the raid and install grub manually. – thatjuan Mar 1 at 7:46

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