I currently have Ubuntu desktop installed on a hard disk. I want to partition the hard disk so that I can reserve 30GB for Ubuntu server and 30GB for Ubuntu desktop. The drive has 300GB available. Right now I am booting from dvd drive and installing ubuntu server. I selected "Guided partitioning" and created a 30GB primary partition of Ext4 journaling filesystem, set "yes, format it" for format partition and set bootable flag to on. I intend to use this 30 gig partition to hold ubuntu server and allow me to boot from it.

Now I have two other partitions. They are both set to "logical", one is currently using 285.8 gigs and is using ext4 (when I try to set bootable flag to true, it gives a warning "You are trying to set the bootable flag on a logical partition. The bootable flag is only useful on the primary partitions"). More alarming it says "No existing file system was detected in this partition". Actually, Im thinking that this is the partition that is supposed to be holding my current Ubuntu Desktop. And of course I want this to be bootable and be a primary partition, so I could dual boot from this and the server partition.

Now the third partition is also set to logical and it is being used as swap area.

How do I switch the second partition to primary and to make sure that its pointing to my existing desktop installation?


Shrink some space as per your requirement from your logical drive having 285.8 GB. Use free space for making Primary partition for ubuntu server.You can use gparted tool for that. This post will help you.

  • But what about my existing Ubuntu Desktop installation? Where is it? I want to be able to boot from that too – JohnMerlino Oct 18 '12 at 4:17
  • I create another primary partition, but why is it allowing only one of the primary partitions to be bootable? I want to be able to boot from Ubuntu Desktop and Ubuntu Server. – JohnMerlino Oct 18 '12 at 4:26
  • The boot flag is mostly meaningless. You are almost certainly running GRUB which is installed to the MBR. The boot flag only matters if you have the old MS-DOS style boot loader. – Zoredache Oct 18 '12 at 8:04
  • After configuring grub you will be able to boot both systems. – Ketan Patel Oct 18 '12 at 12:04

ubuntu is able to boot from both logical and primary partitions....its better if you leave primary partitions for installing other os like windows....and for ubuntu use logical only


Linux can boot from either primary or logical partitions.

Windows will install only on primary partitions, if this has not been changed in Windows 8.

"Boot" flag does not mean anything for linux, it is read only by Windows.

If you use multiple OS's, you just install grub on the "whole disk", and it will take care of booting all OS's.

You can't switch a logical partition to primary, but there is no need to do it.

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