Ubuntu – “the partition is misaligned” error in Disk Utility – should I repartition

The older hard drives used smaller 512-byte sectors; recently newer drives use larger sectors, usually 4096 bytes.

Software, however, is still sees the disk in 512-byte "logical" sectors, although it often reads the data in 4K chunks

When creating a partition, it is important to align the beginning of the partition with the beginning of the large physical sector, otherwise each read will require reading 2 physical sectors, which will affect performance.

As you can see, your partition starts from logical sector #3 (#1 and #2 take 512*2=1024 bytes), so to fix the problem you need to move the start of the partition by 3072 (4096-1024) bytes.

Newer versions of gparted are aware of this - just boot from Ubuntu LiveCD and create a new partition selecting the default alignment option (which is "align to 1 MB", which is optimal even for larger sector size, such as in SSDs).

If you already installed OS and do not want to re-create partitions, you could move the start of the partitions to align properly, but that would involve some pen-and-paper calculations. Also, you'll need to reinstall the bootloader if you moved Ubuntu partition.

This article explains this problem.

The problem with misalignment lies with the partition editor. The partition editor that was used during installation defaulted to Rounding off to nearest cylinder. Whereas for newer installers it defaults to Rounding off to nearest MB.

Possible solutions ...

• Back up, repartition, and restore.
• Repartition and reinstall.
• Use GParted to resize/move the partition that has a problem without backup.

Here is the official document on resizing. It is old though and does not include the dropdownbox regating the MiB setting. Another one without images.