# Partition table entries are not in disk order



## cola (Nov 29, 2010)

After installing freebsd, from linux system doing fdisk -l  i get partitions are not in disk order:
from freebsd fdisk ad6 i get warning too.

```
Warning: BIOS sector numbering starts with sector 1
```
How can i fix it?


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## cola (Nov 29, 2010)

```
Partition 3 does not end on cylinder boundary.
```


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## jem (Nov 29, 2010)

These are just warnings.  You can most likely ignore them.

Back in days of old, MBR partitions were supposed to be aligned to cylinders on the disk.  In these modern days of Logical Block Addressing, and of the real geometry of disks being completely different to the reported geometry, aligning partitions is pointless and almost impossible.


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## Galactic_Dominator (Dec 2, 2010)

jem said:
			
		

> Back in days of old, MBR partitions were supposed to be aligned to cylinders on the disk.  In these modern days of Logical Block Addressing, and of the real geometry of disks being completely different to the reported geometry, aligning partitions is pointless and almost impossible.



I suggest reading this thread and being more careful with your advice.  It's generally quite easy to do if you can manage basic addition and subtraction and it's very important for certain types of disks e.g. SSD, USB flash, WD EARS.  GPT/MBR scheme is irrelevant to the need for partition alignment as misalignment on either can cause a large performance hit.

http://lists.freebsd.org/pipermail/freebsd-current/2009-December/014534.html


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## jem (Dec 2, 2010)

Galactic_Dominator said:
			
		

> I suggest reading this thread and being more careful with your advice.  It's generally quite easy to do if you can manage basic addition and subtraction and it's very important for certain types of disks e.g. SSD, USB flash, WD EARS.  GPT/MBR scheme is irrelevant to the need for partition alignment as misalignment on either can cause a large performance hit.
> 
> http://lists.freebsd.org/pipermail/freebsd-current/2009-December/014534.html



The need for partitions to be aligned to sector-multiples on SSD's and Advanced Format disks is a completely different issue to the age-old reason for MBR partitions to be aligned to cylinders.  This warning about a partition not ending on a cylinder boundary refers to that, I think.


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## Galactic_Dominator (Dec 2, 2010)

jem said:
			
		

> The need for partitions to be aligned to sector-multiples on SSD's and Advanced Format disks is a completely different issue to the age-old reason for MBR partitions to be aligned to cylinders.  This warning about a partition not ending on a cylinder boundary refers to that, I think.


Well it's really not.  In terms of CHS alignment, of course that is dead and has been for a long time but partition alignment is still very important.


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