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I am using ubuntu 20.04 and I want to create new partition disk with exactly 500 MB. However, the fdisk adjusted it to 512MiB is there any way that I can create exactly 500MB disk size?

fdisk output

ric@Eric:~/Downloads$ sudo fdisk /dev/sda

Welcome to fdisk (util-linux 2.34).
Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.


Command (m for help): n
All primary partitions are in use.
Adding logical partition 7
First sector (2359260-10288994, default 2359260): 2359260
Last sector, +/-sectors or +/-size{K,M,G,T,P} (2359260-10288994, default 10288994): +500M


Created a new partition 7 of type 'Linux' and of size 512 MiB.


Command (m for help): p
Disk /dev/sda: 931.53 GiB, 1000204886016 bytes, 1953525168 sectors
Disk model: Portable SSD T5 
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 33553920 bytes
Disklabel type: dos
Disk identifier: 0xd13fa933


Device     Boot      Start        End   Sectors   Size Id Type
/dev/sda1  *    1952501760 1953523711   1021952   499M ef EFI (FAT-12/16/32)
/dev/sda2       1950453760 1952501759   2048000  1000M 83 Linux
/dev/sda3       1704693760 1950453759 245760000 117.2G 83 Linux
/dev/sda4            65536   10288994  10223459   4.9G  5 Extended
/dev/sda5           131071    1179629   1048559   512M 83 Linux
/dev/sda6          1245165    2293724   1048560   512M 83 Linux
/dev/sda7          2359260    3407819   1048560   512M 83 Linux


Partition table entries are not in disk order.


Command (m for help):
Sajjan Singh
  • 103
Eric Steven
  • 33
  • hello i am using ubuntu 20.04 i used the command +500M however the result is 512MiB is it possible to actuallly made exactly 500M parition ? – Eric Steven Jan 03 '21 at 07:58

1 Answers1

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This can be solved with math! The sectors are 512 bytes in size, which means you need a million to have 500MB.

First sector (2359260-10288994, default 2359260): 2359260
Last sector, +/-sectors or +/-size{K,M,G,T,P} (2359260-10288994, default 10288994): 3359260

However, be prepared for the number to not be exactly 500MB if:

  • the storage controller on the SSD does not like the number
  • the storage controller on the main board does not like the number

A lot of math has gone into how data is written and organized on storage devices over the years and there are some situations that are suboptimal for the long-term use of a device.