On 24.05.2011 21:27, Victor Balada Diaz wrote: >>> 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?
BSD slice provider. > If i understood it correctly, it would be like: > > Sector 0: usual IBM-PC MBR, MBR provider doesn't need anything more > Sector 1-62: Reserved by MBR scheme (dunno why, but seems to be the case, > probably CHS alignment) start: 63 Yes, currently we are actively discussing about this in the freebsd-geom@ maillist. > Sector 63: BSD scheme unused because on disk metadata is stored on second > sector Here is saved the boot1 stage of /boot/boot. > Sector 64: BSD scheme (disklabel) on disk data (148 + 8 * 16 = 276 bytes > according to sys/disklabel.h) GEOM_PART_BSD supports up to 20 partitions. > Sectors 65-(63+16): Reserved by ??? for /boot/boot Here is saved the boot2 stage of /boot/boot. > Sectors (63+16)+: partitions If you will not use offset for the first BSD partition, then you can wipe BSD scheme with this command: # dd if=/dev/zero of=/dev/da0s1a count=2 -- WBR, Andrey V. Elsukov
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