Linode’s pv-grub Library article covers Ubuntu 10.04 and 11.04, but not 12.04. Having recently used pv-grub on EC2, and for other reasons, I wanted to try it out. Putting together the Library article, Linode’s old wiki, EC2’s configuration, and the effects of sleep deprivation and caffeine, here’s what I came up with.
Doing this was, surprise surprise, more fun than writing about it, so this post will be as short and nonsweet as I can make it.
$ sudo aptitude install grub-legacy-ec2
$ sudoedit /boot/grub/menu.lst
Edit menu.lst roughly like this:
--- menu.lst~ 2013-03-10 00:18:09.000000000 +0000 +++ menu.lst 2013-03-10 00:21:40.000000000 +0000 @@ -17,7 +17,7 @@ # Set a timeout, in SEC seconds, before automatically booting the default entry # (normally the first entry defined). # on ec2, with no console access, there is no reason for a timeout. set to 0. -timeout 0 +timeout 10 ## hiddenmenu # Hides the menu by default (press ESC to see the menu) @@ -64,7 +64,7 @@ ## e.g. kopt=root=/dev/hda1 ro ## kopt_2_6_8=root=/dev/hdc1 ro ## kopt_2_6_8_2_686=root=/dev/hdc2 ro -# kopt=root=UUID=f63cf0b4-8c2b-4327-a213-e7f5b8634c27 ro +# kopt=root=/dev/xvda ro ## default grub root device ## e.g. groot=(hd0) @@ -83,7 +83,7 @@ ## additional options to use with the default boot option, but not with the ## alternatives ## e.g. defoptions=vga=791 resume=/dev/hda5 -# defoptions=console=hvc0 +# defoptions=console=hvc0 rootflags=nobarrier ## should update-grub lock old automagic boot options ## e.g. lockold=false
Increasing timeout gives you 10 seconds to log into lish and choose which kernel you want while booting.
Changing the kopt line – your filesystem’s UUID will be different – is necessary because Linode might change the UUID (e.g. if you restore from a backup), so it’s safer to specify /dev/xvda.
rootflags=nobarrier avoids a compatibility issue between newer kernels like Ubuntu Precise’s and less-newer Linode hosts that would otherwise make your fs go read-only and ruin your day.
$ sudoedit /etc/fstab
Add barrier=0 to your filesystem mount options, like so:
--- fstab~ 2013-03-10 03:45:18.000000000 +0000 +++ fstab 2013-03-10 03:45:23.000000000 +0000 @@ -6,6 +6,6 @@ # # <file system> <mount point> <type> <options> <dump> <pass> proc /proc proc defaults 0 0 -/dev/xvda / ext3 noatime,errors=remount-ro 0 1 -/dev/xvdb /home ext3 noatime,errors=remount-ro 0 2 +/dev/xvda / ext3 noatime,errors=remount-ro,barrier=0 0 1 +/dev/xvdb /home ext3 noatime,errors=remount-ro,barrier=0 0 2 /dev/xvdc none swap sw 0 0
This is for the same reasons as the rootflags=nobarrier stuff above. I think you can skip it on the root fs, but it won’t hurt, and you definitely need it on any secondary filesystems.
$ sudo aptitude install linux-virtual
After downloading and installing roughly half of the repository, this will eventually pop up a curses interface asking you to install grub-pc on your MBR. You do not have an MBR. Hit Enter without selecting any of the devices to get through the first screen, then hit Left and Enter to select <Yes> in the confirmation screen.
From here, you can switch to the Linode Library guides for 10.04 or 11.04, starting with the line “Create the file /etc/init/hvc0.conf with the following contents.”. (That file may already exist, but in any case, you do need to follow the later instructions.)
(Caveat: menu.lst includes entries to boot into single-user mode. They are broken. This would not be hard to fix – see defoptions and kopt – but my heart belongs to Finnix, so I don’t care.)
(Edits: Copy editing.) (Edit, 2013-03-10T03:54:43Z: Elaborate on /etc/fstab and barrier=0. Remove note about single-user mode – it seems to work?) (Edit, 04:09:12Z: Wait, no, single-user mode doesn’t work. Elaborate.)
