GPT and disk alignment

Jeremy Chadwick freebsd at
Wed Jun 8 05:10:07 UTC 2011

On Tue, Jun 07, 2011 at 11:29:32PM -0500, Mark Felder wrote:
> On Tue, 07 Jun 2011 22:27:24 -0500, Robert Simmons
> <rsimmons0 at> wrote:
> >Do all HDDs that have 4KB per LBA present themselves to the OS as
> >having 512 bytes per LBA?
> No
> >What about SSDs that have 1024 bytes per LBA?
> Not sure, but I do know that not all flash media have the same bytes
> per LBA internally. Some are 1K, some 4K, some even 8K. GPT is
> definitely the way to go if you want to make sure you're aligned.

Maybe I've misread what you've wrote, but since when was GPT a
requirement for partition boundary alignment?

| Jeremy Chadwick                                   jdc at |
| Parodius Networking              |
| UNIX Systems Administrator                   Mountain View, CA, US |
| Making life hard for others since 1977.               PGP 4BD6C0CB |

More information about the freebsd-fs mailing list