I am currently trying to install ubuntu on an external hdd. (Seagate Expansion 2TB USB 3.0). And I am rather new to Linux installations.

Since my laptop does not have a cd drive I downloaded the iso, created a new partition (4Gb) on one of my internal drives, installed refind and rebooted the device. This works fine (following this guide)

The Problem

The problem occures when I try to install ubuntu. After the setup window opens, I click trough until I can "Choose something else" where I can partition my previously not formatted hdd.

I then created a 25 GB partition for the os in ext4 and a swap of the same size. I then chose the newly created partition as the palce for the bootloader.

The program then complained that the partition is not aligned and I should redo the whole procedure. So I did. The result was the same.

What I tried

I then searched into this alignment stuff. I mainly oriented myself with this guide. (Look into the comments. A user named Nova deViator apparently had the same hdd as me)

I closed the installation and followed the instructions of the guide. I calculated that the partition starting sector should be 8191.875. This is not possible. Multiplying this number a few times shows that 65535 is the nearest natural number. So I used that to create a new ext4 partition of 25Gb. GParted even attested me that this partition may not be minimally aligned but that it is optimally aligned.

Knowing this I started the installation process anew, chose "Something else" and saw my partition... in ext4... i chose this to be the location og my boot loader, hit install now... and was told i should mount the device first. I clicked "change" changed usage from "not used" to ext4 and mount to "/".

The i clicked "install now" again and lo and behold: got the same alignment error as before. I tried to just ignore it but the offered "continue" button just returns me to the partitioning menu seemingly doing nothing.


I am at the point where I'd say "screw it i use an internal drive". But I'd rather not do this as its much cooler to have a ready os with all your stuff with you at all times.

So is my hdd just shitty? Can I circumvent the whole partitioning screen or trigger the installation via the terminal? Did I understand something fundamentally wrong?


Some Numbers of my hdd

    cat /sys/block/sdb/queue/optimal_io_size
    cat /sys/block/sdb/queue/minimum_io_size
    cat /sys/block/sdb/alignment_offset
    cat /sys/block/sdb/queue/physical_block_size

You have a native 4K disk (aka "advanced format"). The installer seems to be disoriented; for reasons unknown the disk reports a wrong optimal I/O size, and the installer, being a simple minded program, believes it.

(This is actually quite common when installing on a storage device which is not a plain old 512-byte-per-sector disk. I've seen it on a Kingston SSD, for example.)

Don't believe the message about alignment; in particular, the optimal_io_size of 33553920 bytes is manifestly obviously bogus: that number translates to 32 MiB − 512 bytes, which is impossible on a native 4K disk; such a disk cannot read or write less than 4 KiB!

Instead, make sure your partitions are aligned to a multiple of 4 KiB (or 1 MiB if you want to be very conservative).

If you are installing the desktop version of Ubuntu I would suggest booting into a live session ("Try Ubuntu"), then making the partition(s) using Gparted (it's preinstalled in the live session), then start the installation and choose "Manual" partitioning and ignore the bogus message about misalignment.

  • The thing is that the installation tool does not allow me to ignore it. – zetain Dec 23 '17 at 17:09
  • The partition /dev/sdc1 assigned to / starts at an offset of 512 bytes from the minimum alignment for this disk, which may lead to very poor performance. Since you are formatting this partition, you should correct this problem now by realigning the partition, as it will be difficult to change later. To do this, go back to the main partitioning menu, delete the partition, and recreate it in the same position with the same settings. This will cause the partition to start at a point best suited for this disk. At this point I am given the option to "continue" or to "go back" – zetain Dec 23 '17 at 17:15
  • both lead me back to the menu and nothing happens – zetain Dec 23 '17 at 17:16
  • @zetain: Then you should file a bug against the installer. – AlexP Dec 23 '17 at 19:52

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.