g_vfs_open and bread(devvp, ...)

Jeremy Chadwick freebsd at jdc.parodius.com
Fri Mar 26 16:28:58 UTC 2010

On Fri, Mar 26, 2010 at 08:28:10AM -0700, Kirk McKusick wrote:
> I have reviewed your change and I believe that your analysis is
> correct. I am in agreement with your making the change.
> As disk sector sizes will be growing in the near future, it would
> be desirable to get away from having DEV_BSIZE hard-coded. But as
> you note, that is a far bigger change than this one.

I should note that they already have grown: Western Digital, as of a few
months ago, began shipping drives that use 4KByte sectors.  They're
known as the "EARS" drives, due to their model string ending with

WD20EARS: http://www.wdc.com/en/products/Products.asp?DriveID=773
WD15EARS: http://www.wdc.com/en/products/products.asp?driveid=772
WD10EARS: http://www.wdc.com/en/products/products.asp?driveid=763

(I should warn folks these are Caviar Green drives, which may suffer
from excessive Load Cycles (parking/unparking actuator arm).  I don't
have one of these drives so I can't validate if the issue happens on
this model or not)

A discussion and an including an incredibly cheesy video review are
below.  The video review does discuss the 4KB sector size, in addition
to jumpers that revert the drive to using 512-byte sectors for older
OSes such as Windows XP -- and presumably FreeBSD.


| Jeremy Chadwick                                   jdc at parodius.com |
| Parodius Networking                       http://www.parodius.com/ |
| UNIX Systems Administrator                  Mountain View, CA, USA |
| Making life hard for others since 1977.              PGP: 4BD6C0CB |

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