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Date:      Thu, 24 May 2012 08:16:26 -0400
From:      Andrew Duane <aduane@juniper.net>
To:        Tim Kientzle <tim@kientzle.com>, Warren Block <wblock@wonkity.com>
Cc:        "freebsd-hackers@freebsd.org" <freebsd-hackers@freebsd.org>, Apitz <guru@unixarea.de>, Matthias
Subject:   RE: proper newfs options for SSD disk
Message-ID:  <AC6674AB7BC78549BB231821ABF7A9AEB82FBA1E2A@EMBX01-WF.jnpr.net>
In-Reply-To: <CF851064-F78F-44AF-B562-32012E4DC043@kientzle.com>
References:  <alpine.BSF.2.00.1205182209010.9350@wojtek.tensor.gdynia.pl> <4fb7dfd6.736a980a.186d.ffff902f@mx.google.com>	<20120519180901.GA1264@tiny> <4fb7e819.6968700a.7a7f.ffff9153@mx.google.com>	<20120522061734.GA1210@tiny> <alpine.BSF.2.00.1205220731070.51493@wonkity.com> <20120522134846.GA2274@tiny> <alpine.BSF.2.00.1205220837500.51493@wonkity.com> <CF851064-F78F-44AF-B562-32012E4DC043@kientzle.com>

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> -----Original Message-----
> From: owner-freebsd-hackers@freebsd.org [mailto:owner-freebsd-hackers@fre=
ebsd.org] On Behalf Of Tim Kientzle
> Sent: Thursday, May 24, 2012 12:49 AM
> To: Warren Block
> Cc: freebsd-hackers@freebsd.org; Matthias Apitz
> Subject: Re: proper newfs options for SSD disk
>=20
> GPart's alignment option doesn't work for MBR slices.
> It rounds to the requested alignment, and then rounds again
> to the track size, which defaults to 63 sectors.
>=20
> I'm not convinced this is a bug in the design of MBR.  I don't
> think anything in the MBR design requires that partitions
> be track-aligned.
>=20
> Tim

It really doesn't. This is old school thinking based around minimizing seek=
 and rotation time on slow multiplatter HDDs. It also helped the redundant =
superblock layout scheme of UFS make that spiral striping down a set of dis=
k platters. My bet is no one has ever bothered to rethink this in the 25 ye=
ars since....


...................................
Andrew Duane
Juniper Networks
+1 978-589-0551 (o)
+1 603-770-7088 (m)
aduane@juniper.net

=A0






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