Create partition aligned using parted

gptpartition

I'm partitioning a non-SSD hard disk with parted because I want a GPT partition table. 

parted /dev/sda mklabel gpt

Now, I'm trying to create the partitions correctly aligned so I use the following command to know where the first sector begins:

parted /dev/sda unit s p free

Disk /dev/sda: 488397168s
Sector size (logical/physical): 512B/512B
Partition Table: gpt

Number  Start  End         Size        File system  Name      Flags
        34s    488397134s  488397101s  Free Space

We can see that it starts in sector 34 (that's the default when this partition table is used).

So, to create the first partition I tried:

parted /dev/sda mkpart primary 63s 127s

to align it on sector 64 since it's a multiple of 8 but it shows:

Warning: The resulting partition is not properly aligned for best performance.

The logical and physical sector sizes in my hard disk are both 512 bytes:

cat /sys/block/sda/queue/physical_block_size
512

cat /sys/block/sda/queue/logical_block_size 
512

How do I create partitions correctly aligned? What am I doing wrong?

Best Answer

In order to align partition with parted you can use --align option. Valid alignment types are:

  • none - Use the minimum alignment allowed by the disk type.
  • cylinder - Align partitions to cylinders.
  • minimal - Use minimum alignment as given by the disk topology information. This and the opt value will use layout information provided by the disk to align the logical partition table addresses to actual physical blocks on the disks. The min value is the minimum alignment needed to align the partition properly to physical blocks, which avoids performance degradation.
  • optimal Use optimum alignment as given by the disk topology information. This aligns to a multiple of the physical block size in a way that guarantees optimal performance.

Other useful tip is that you can set the size with percentages to get it aligned. Start at 0% and end at 100%. For example:

parted -a optimal /dev/sda mkpart primary 0% 4096MB

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