[DragonFlyBSD - Bug #2830] gpt(8) doesn't align partitions to 1MB blocks

[bugtracker-admin at leaf.dragonflybsd.org]

Issue #2830 has been updated by sepherosa.


I'd say align on 8MB at least; modern flash chips have >=4MB erase
span.  Even 8MB probably will not be good after several years for SSD.

On Wed, Jul 1, 2015 at 4:41 AM,  <bugtracker-admin at leaf.dragonflybsd.org> wrote:
> Issue #2830 has been updated by ftigeot.
>
> Related to Bug #2674: GPT Support added
>
> ----------------------------------------
> Bug #2830: gpt(8) doesn't align partitions to 1MB blocks
> http://bugs.dragonflybsd.org/issues/2830#change-12687
>
> * Author: ftigeot
> * Status: New
> * Priority: Normal
> * Assignee:
> * Category:
> * Target version:
> ----------------------------------------
> The GPT partition scheme management utility, gpt(8) doesn't manage partition alignment at all.
>
> # gpt create /dev/da1
> # gpt boot /dev/da1
> # gpt show /dev/da1
>       start       size  index  contents
>           0          1      -  PMBR
>           1          1      -  Pri GPT header
>           2         32      -  Pri GPT table
>          34    2097152      0  GPT part - DragonFly Label32
>
> We can see the just created boot partition starts on the legacy sector 34 offset, 17KB from the start of the device.
>
> This isn't divisible by the physical sector size of modern disk devices (4KB).
> It isn't optimal with SSD either: they typically use 8KB or bigger erase blocks.
>
> gpt(8) should behave in the same as disklabel64 and align partitions to 1MB boundaries.
>
>
>
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-- 
Tomorrow Will Never Die

----------------------------------------
Bug #2830: gpt(8) doesn't align partitions to 1MB blocks
http://bugs.dragonflybsd.org/issues/2830#change-12690

* Author: ftigeot
* Status: New
* Priority: Normal
* Assignee: 
* Category: 
* Target version: 
----------------------------------------
The GPT partition scheme management utility, gpt(8) doesn't manage partition alignment at all.

# gpt create /dev/da1
# gpt boot /dev/da1
# gpt show /dev/da1
      start       size  index  contents
          0          1      -  PMBR
          1          1      -  Pri GPT header
          2         32      -  Pri GPT table
         34    2097152      0  GPT part - DragonFly Label32

We can see the just created boot partition starts on the legacy sector 34 offset, 17KB from the start of the device.

This isn't divisible by the physical sector size of modern disk devices (4KB).
It isn't optimal with SSD either: they typically use 8KB or bigger erase blocks.

gpt(8) should behave in the same as disklabel64 and align partitions to 1MB boundaries.



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