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Date:      Tue, 19 Jul 2011 12:37:34 -0700
From:      Chuck Swiger <cswiger@mac.com>
To:        "freebsd-stable@freebsd.org Stable" <freebsd-stable@freebsd.org>
Subject:   Re: Status of support for 4KB disk sectors
Message-ID:  <19976EC2-462E-4B2E-AD57-57EC0921A0BF@mac.com>
In-Reply-To: <j04lvs$bf4$1@dough.gmane.org>
References:  <CAN6yY1uaUqk2ifiNViJyMFJWf60a4DmCiVs3Z=--_TjtzseABQ@mail.gmail.com> <20110718234124.GA5626@icarus.home.lan> <CAN6yY1uaEwoEhEuoTNPqzywRaCPEvcLY-ddyFRUV00FcBDU1BA@mail.gmail.com> <E8F5CB22-21D5-4AF9-A690-1DB99D31F4CC@mac.com> <j04lvs$bf4$1@dough.gmane.org>

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On Jul 19, 2011, at 12:29 PM, Ivan Voras wrote:
>> Is there something in FreeBSD which is preventing you from using the drive's native DEV_BSIZE of 4096 bytes, or is it that the drive claims to have a physical block size of 512 bytes when it is really 4k?
> 
> Nope, "only" that.

:-)

It's nice to have well-defined problems-- although it's perhaps not so nice when hardware is compelled to lie about its status because of backwards-compatibility (C/H/S vs LBA comes to mind also).

> The current state of the matter (i.e. for 9.0) is:
> 
> * The new ATA driver has quirks for certain models of HDDs which have this false advertising (which can be manually triggered by kern.cam.ada.X.quirks=1) which causes the drive to report stripesize of 4k.
> 
> * This information is used in gpart to size & align partitions; it will be used by the new installer
> 
> * Default fragment size for UFS was raised to 4K so it will be aligned by default.

Excellent; thanks for the detailed reply.

Regards,
-- 
-Chuck




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