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Old 27th October 2008
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jggimi jggimi is offline
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Join Date: May 2008
Location: USA
Posts: 7,977
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Getting back on topic for php111, starting with a little level-setting. Please excuse me if this is review, php111:

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The MBR (sector #0 on a hard drive) contains a small boot program and a partition table, holding only enough information to manage four partitions. When you "boot" a hard drive on an architecture that uses MBR, the BIOS loads this sector into memory, and if a valid MBR program is found, passes control to it. To get more than four partitions, a primary partition may be pointed at an extended partition table to further carve up the disk.

The MBR area includes not only sector #0, but the rest of the sectors in that track (0-62). This area is not used by operating systems, so it may be used for things like multiboot managers, and extended partition tables.

The MBR partitioning system is used at a different "layer" than OpenBSD's partitioning system. Briefly, on MBR architectures you assign a single MBR partition to OpenBSD. If OpenBSD is the only OS using the drive, you assign that MBR partition to the entire drive.

Whether or not MBR partitions are used, BSD uses the disklabel to manage it's own partitioning. MBRs were an invention dating back to the IBM PC/XT, but they are still used today on about six different architectures, such as the commonly used i386 and amd64 archs, as well as zaurus, landisk, even macppc.

Beginning with 4.4, OpenBSD may be installed in an extended partition if necessary.
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If your hard drive has unallocated space, you can create a new MBR partition for it in that space.

If your hard drive does not have any unallocated space left, you will have to "resize" either your C: or your H: drive. This may or may not be easy, depending on the filesystem in use. If you're using FAT32, then you can "shrink" the data in a partition with the fips program, found in the /pub/OpenBSD/<release>/tools/fips directory at your nearest mirror.

If you are using NTFS, then you will have to use another method. There are 3rd party commercial products, such as Partition Magic, or Linux and gpartd ... but the easiest way, I would think, would be by backing up the 3GB in use on your H drive, make it smaller, (e.g.: 4GB), restore the data, then use newly unallocated space for OpenBSD.
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