User: Password:
Subscribe / Log in / New account

Re: ATA 4 KiB sector issues.

From:  "Martin K. Petersen" <>
To:  Tejun Heo <>
Subject:  Re: ATA 4 KiB sector issues.
Date:  Mon, 08 Mar 2010 10:18:27 -0500
Cc:  "" <>, lkml <>, Daniel Taylor <>, Jeff Garzik <>, Mark Lord <>,, "H. Peter Anvin" <>,, Andrew Morton <>, Alan Cox <>,, Matthew Wilcox <>,,,, Karel Zak <>, Jim Meyering <>
Archive-link:  Article, Thread

>>>>> "Tejun" == Tejun Heo <> writes:

Tejun> The [Windows Vista/7] partitioner seems to be using 1M as the
Tejun> basic alignment unit and offsetting from there if explicitly
Tejun> requested by the drive


Tejun> Please note that hdparm is misreporting the alignment offset.  It
Tejun> should be reporting 512 instead of 256 for offset-by-one drives.

Already fixed.  Your hdparm must be old.

Tejun> Partitioners maybe should only align partitions which will be
Tejun> used by Linux and default to the traditional layout for others
Tejun> while allowing explicit override.

I don't think we take the partition type into account.  Karel?

Tejun> Reportedly, commonly used partitioners aren't ready to handle
Tejun> drives larger than 2 TiB in any configuration and alignment isn't
Tejun> done properly for drives with 4 KiB physical sectors.  4 KiB
Tejun> logical sector support is broken in both the kernel 

Huh, what?  My homedir is on a 4KiB LBS/PBS drive and has been for ~2

Tejun> (need more details and probably a whole section on partitioner
Tejun> behaviors)

I'm Cc:'ing Karel Zak and Jim Meyering who have been doing all the
alignment work for fdisk and parted respectively.  Karel, Jim: The full
writeup is here:

It'd be great if you guys could share what you have been doing to the

Tejun> Unfortunately, the transition to 4 KiB sector size, physical only
Tejun> or logical too, is looking fairly ugly.  Hopefully, a reasonable
Tejun> solution can be reached in not too distant future but even with
Tejun> all the software side updated, it looks like it's gonna cause
Tejun> significant amount of confusion and frustration.

With regards to XP compatibility I don't think we should go too much out
of our way to accommodate it.  XP has been disowned by its master and I
think virtualization will take care of the rest.

FWIW, recent fdisk has a command line flag that will enable/disable DOS
compatible layout.

Martin K. Petersen	Oracle Linux Engineering
To unsubscribe from this list: send the line "unsubscribe linux-ide" in
the body of a message to
More majordomo info at

(Log in to post comments)

Copyright © 2010, Eklektix, Inc.
Comments and public postings are copyrighted by their creators.
Linux is a registered trademark of Linus Torvalds