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Date:      Tue, 12 Mar 2013 21:49:22 +1100 (EST)
From:      Bruce Evans <brde@optusnet.com.au>
To:        Bruce Evans <brde@optusnet.com.au>
Cc:        freebsd-fs@freebsd.org
Subject:   Re: Aligning MBR for ZFS boot help
Message-ID:  <20130312213522.R1412@besplex.bde.org>
In-Reply-To: <20130312203745.A1130@besplex.bde.org>
References:  <513C1629.50501@caltel.com> <alpine.BSF.2.00.1303101006490.5989@wonkity.com> <513CD9AB.5080903@caltel.com> <alpine.BSF.2.00.1303101326530.7218@wonkity.com> <513CE369.4030303@caltel.com> <alpine.BSF.2.00.1303101349540.7637@wonkity.com> <1362951595.99445.2.camel@btw.pki2.com> <alpine.BSF.2.00.1303101807550.8481@wonkity.com> <CABXB=RTt-j0SGxktWMfLcgLAEN6Vi%2Bf=psBuN0jQaJthk_3cbw@mail.gmail.com> <513E1208.5020804@caltel.com> <20130312203745.A1130@besplex.bde.org>

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On Tue, 12 Mar 2013, Bruce Evans wrote:

> Last time I looked, Linux fdisk[s] worked better on FreeBSD than FreeBSD
> fdisk, partly because they don't depend on special ioctls, so that they
> know that they don't know the BIOS geometry.  Specifying the geometry is
> so routine that it is a command-line parameter in all Linux fdisks in
> FreeBSD ports (at least in old versions).

Just tried an old version of them on my version of an old version of
FreeBSD.  They worked not so well:

- fdisk-linux: worked OK except for bogus warnings about > 1024 cylinders
   and a not so bogus warning about a slice not ending on a cylinder
   boundary.  The slice just ends at the end of the disk, and since the
   cylinders are fake that happens not to be a cylinder boundary.  The
   disk has a firmware fake geometry of 63 sectors 16 heads and mumble
   cylinders, and the disk manufacturer throws away sectors at the end
   to make it end on a cylinder boundary with these fake cylinders, but
   I use different fake cylinders.  FreeBSD, Linux and WinXP don't care
   about the slice not ending on a cylinder boundary.
- sfdisk-linux: refused to start without write permission
- cfdisk-linux: refused to start due to 1 slice not ending on a cylinder
   boundary.  With its -z workaround for not starting, it starts but is
   useless since it doesn't display the existing partitions.

Bruce



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