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Ok. I want to install Ubuntu on an external hard drive as my sole operating system. I have a HP Pavillion dv5 laptop with no internal drive. I have been running the trial off a USB stick. When I try to install the full operating system to the external drive it tells me I need to redo the offset of one of the partitions. At this point I am totally lost. Can someone please help me out ?

  • Is there anything else on the drive? Which partition gets the complaint -- one with a filesystem or swap or the extended? Can you just delete them all and install using the default to use whole disk? – ubfan1 Nov 28 '16 at 21:11
  • ok here is the full message I get when I get to that point: The partition /dev/sdb1 assigned to / starts at an offset of 3584 bytes from the minimum alignment for this disk, which may lead to poor performance – Greg Lindsey Nov 28 '16 at 21:18
  • I'm assuming I have to redo the partition but I have no idea how to do this. – Greg Lindsey Nov 28 '16 at 21:54
  • It would help if you posted more information like sudo fdisk -l /dev/sdb or whatever your external disk is. Just guessing, your disk wants a 4096 alignment, so the start should be 4096 when you create a new partition in a partition editing tool like fdisk or gdisk. – ubfan1 Nov 29 '16 at 1:57
  • This is the info I got Disk /dev/sda: 931.5 GiB, 1000204885504 bytes, 1953525167 sectors Units: sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 4096 bytes I/O size (minimum/optimal): 4096 bytes / 33553920 bytes Disklabel type: dos Disk identifier: 0x921181c6 Device Boot Start End Sectors Size Id Type /dev/sda1 65535 983024 917490 448M 83 Linux /dev/sda2 1048558 1953467279 1952418722 931G 5 Extended /dev/sda5 1048560 1953467279 1952418720 931G 8e Linux LVM – Greg Lindsey Feb 25 '17 at 7:49
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You starting byte of sda1 is 65535, which is the last byte of the 128th sector. Your offset error of 3584 is 512 bytes less than 4096. I'd guess your start should be 65536, one more, to start at a sector, and fix the offset. Fix this and redo the install.


You can run with root privs. using the sudo command before the command, and entering your password. If you have been using the live media to run, the ubuntu account initially has the sudo capabilities -- if you added accounts, you would need to enter them into the /etc/sudoers file (from the ubuntu account initially).

If there's nothing on the disk yet, just run the install again, and select something else, then delete the sda1 partition, and re-add it starting one sector higher,65536. Don't use the logical volume unless you really need it, for encryption for example. See recommendation on partitioning. You should make a swap partition, 2G at lease, avoid /boot unless you need it (LVM for instance), make two 50G root partitions (use one, other one is for testing new releases, etc.), and a big data partition you can mount under your home directory. Since you have room, you can also put a 500M partition up front for future use as an EFI partition (move the disk to a new machine sometime). DOS disk partitioning limits you to 4 primary partitions, so make 3 primaries, and an extended for the rest of the logical partitions. Ubuntu does not care what kind of partition it boot from, but I'd use ESP, root, root, extended then in extended, data and swap.

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  • Thank you for the answer. I did an fdisk -l and got the info again but I have no clue about the command to change it. I can't use gdisk because it won't allow me to set up a root account. If you can help one more time with the way to change the start point of the sector to fix the offset it would be greatly appreciated. – Greg Lindsey Feb 26 '17 at 3:55

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