GEOM is the main storage framework for the FreeBSD operating system. It is available in FreeBSD 5.0 and higher and provides a standardized way to access storage layers. GEOM is modular and allows for geom modules to connect to the framework.
Wikipedia: GEOM
FreeBSD Handbook: GEOM: Modular Disk Transformation Framework
# fdisk /dev/da1 ******* Working on device /dev/da1 ******* parameters extracted from in-core disklabel are: cylinders=3892 heads=255 sectors/track=63 (16065 blks/cyl) Figures below won't work with BIOS for partitions not in cyl 1 parameters to be used for BIOS calculations are: cylinders=3892 heads=255 sectors/track=63 (16065 blks/cyl) Media sector size is 512 Warning: BIOS sector numbering starts with sector 1 Information from DOS bootblock is: The data for partition 1 is: sysid 12 (0x0c),(DOS or Windows 95 with 32 bit FAT (LBA)) start 32, size 62530592 (30532 Meg), flag 80 (active) beg: cyl 0/ head 0/ sector 33; end: cyl 1023/ head 254/ sector 63 The data for partition 2 is: <UNUSED> The data for partition 3 is: <UNUSED> The data for partition 4 is: <UNUSED>
# gpart show => 34 29323661 ada0 GPT (14G) 34 128 1 freebsd-boot (64K) 162 27262848 2 freebsd-ufs (13G) 27263010 1466368 3 freebsd-swap (716M) 28729378 594317 - free - (290M) => 1 62533295 da1 MBR (30G) 1 31 - free - (16K) 32 62530592 1 !12 [active] (30G) 62530624 2672 - free - (1.3M) => 1 62533295 diskid/DISK-AA010922140523382836 MBR (30G) 1 31 - free - (16K) 32 62530592 1 !12 [active] (30G) 62530624 2672 - free - (1.3M)