Ubuntu 16.04 EFI Boot Software Raid

Hi

I tried to setup the “EFI System” partition at install time with software RAID1 array. I tried to avoid installing the bootloader to every disk. (I had an RAID1 with spare)

The ubuntu installer allows to set as partition type “EFI System” on the software RAID array. So I thought it would work.

After successful installation the BIOS of the Supermicro mainboard has not found any EFI-Boot partition.

So I destroyed the software RAID of the “EFI System” and installed the bootloader in chroot from a Debian-Live system. I had not to change the partition flag. It was already setup right to “EFI System”

mdadm -S /dev/mdX
mdadm --zero-superblock /dev/sda1
mdadm --zero-superblock /dev/sdb1
mdadm --zero-superblock /dev/sdc1


mkfs.vfat /dev/sda1
mkfs.vfat /dev/sdb1
mkfs.vfat /dev/sdc1

mount /dev/md[RootFileSystemWithBoot] /mnt
mount --bind /dev /mnt/dev
mount --bind /sys /mnt/sys
mount --bind /proc /mnt/proc

chroot /mnt

Now we remove the RAID array from config file

vim /etc/mdadm.conf

Edit your fstab

blkid /dev/sda1
vim /etc/fstab

And last but not least install grub

mount /dev/sda1 /boot/efi
grub-install /dev/sda1
umount /boot/efi

mount /dev/sdb1 /boot/efi
grub-install /dev/sdb1
umount /boot/efi

mount /dev/sdc1 /boot/efi
grub-install /dev/sdc1

update-grub

Hint: You have to use a install media or live system which is EFI Boot capable and force BIOS to boot from UEFI. (You could use my USB Stick). Otherwise EFI support in Linux is disabled.

Have fun!

debian jessie as kvm guest high cpu load

Hi

I was wondering about the high cpu load of my debian jessie kvm guests.

PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+    COMMAND
 18 root 20 0     S           11,0      50:10.35 ksoftirqd/2
 28 root 20 0     S           11,0      49:45.90 ksoftirqd/4
 13 root 20 0     S           10,1      51:25.18 ksoftirqd/1
 23 root 20 0     S           10,1      55:42.26 ksoftirqd/3
 33 root 20 0     S           8,3       43:12.53 ksoftirqd/5
 3 root 20 0      S           7,4       43:19.93 ksoftirqd/0

The more load my kvm guest had the more cpu time was allocated by the kernel.
I was using 3.16.0-4-amd64.

My hostmachines were, ubuntu 14.04 and archlinux. Both same issue.

Simple solution was to install backports kernel 4.2.0-0.bpo.1-amd64 oder compile fresh vanilla kernel via make localyesconfig.

Seems to be a debian kernel bug.

Have fun!