Date: Tue, 24 May 2011 19:27:19 +0200 From: Victor Balada Diaz <victor@bsdes.net> To: "Andrey V. Elsukov" <ae@FreeBSD.org> Cc: stable@freebsd.org Subject: Re: gpart usage Message-ID: <20110524172718.GG1291@equilibrium.bsdes.net> In-Reply-To: <4DDBD73B.7090600@FreeBSD.org> References: <20110524132028.GE1291@equilibrium.bsdes.net> <4DDBC4A9.7040404@FreeBSD.org> <20110524150951.GF1291@equilibrium.bsdes.net> <4DDBD73B.7090600@FreeBSD.org>
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On Tue, May 24, 2011 at 08:05:15PM +0400, Andrey V. Elsukov wrote: > On 24.05.2011 19:09, Victor Balada Diaz wrote: > > On Tue, May 24, 2011 at 06:46:01PM +0400, Andrey V. Elsukov wrote: > >> On 24.05.2011 17:20, Victor Balada Diaz wrote: > >>> also, how do i know about offsets each partitioning scheme needs? shouldn't GEOM > >>> take care of it without user needing to know anything about it? > >> > >> Usually you do not need to know anything about offsets. > > > > So the 16 sector offset in BSD label is really needed or isn't? > > First 8 KBytes of the freebsd partition are reserved for the boot code > (/boot/boot). The table of BSD partitions itself is located in the > second sector. So, if you plan to create freebsd-ufs partition you can > create it without any offset. But if it will be not an UFS partition, > then i would created it with offset, otherwise you can wipe the BSD label. Who's the one reserving the 16 sector (8 KBytes) offset? the UFS filesystem? the BSD slice/disklabel provider? the MBR provider? If i understood it correctly, it would be like: Sector 0: usual IBM-PC MBR, MBR provider doesn't need anything more Sector 1-63: Reserved by MBR scheme (dunno why, but seems to be the case, probably CHS alignment) start: 63 Sector 64: BSD scheme unused because on disk metadata is stored on second sector Sector 65: BSD scheme (disklabel) on disk data (148 + 8 * 16 = 276 bytes according to sys/disklabel.h) Sectors 65-81: Reserved by ??? for /boot/boot Sectors 82+: UFS/other FS data Is this right or i'm mistaken? -- La prueba más fehaciente de que existe vida inteligente en otros planetas, es que no han intentado contactar con nosotros.
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