DragonFlyBSD

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@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.

1. gpt create /dev/da1
2. gpt boot /dev/da1
3. 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.

--
You have received this notification because you have either subscribed to it, or are involved in it.
To change your notification preferences, please click here: http://bugs.dragonflybsd.org/my/account

--
Tomorrow Will Never Die

Thanks for the patch, it appears to work perfectly so far.

Do you have a name you'd like to use for the commit besides "Charlie Root" ?