Hi,
When I refer to gpart(8) manpage (9.1 release, updated jan 25,2013), I
find the description of partition types a bit confusing.
Considering the case of a MoBo with "old way" Bios (non UEFI), the only
scheme allowed to get a bootable system is MBR. (Note that after
booting, your OS is able to manage gpt-scheme on different providers.)
Then, if you speak "bsd-ish", you are able to add on the "MBR"-scheme
provider up to 4 "freebsd-type" slices, each of them containing up to 8
partitions with a BSD filesystem (or swap space).
Or, if you speak "msdos-ish", you would be able to add on the "MBR"
provider up to 4 "msdos-type" partitions (or 3 + 1 extended ), each of
them containing one filesystem.
The manpage does'nt list explicitly the type for this second case;
Oliver try to use "mbr", decribed as "A partition that is
sub-partitioned by a Master Boot Record (MBR). This type is known as
"!024dee41-33e7-11d3-9d69-0008c781f39f " by GPT.". Such definition is'nt
very explicit.
Let me show the example below on my provider ada0 :
$ gpart show
=> 63 976773105 ada0 MBR (465G)
63 136314864 1 freebsd [active] (65G)
136314927 840458241 - free - (400G)
=> 0 136314864 ada0s1 BSD (65G)
0 8388608 1 freebsd-ufs (4.0G)
8388608 16777216 2 freebsd-swap (8.0G)
25165824 16777216 4 freebsd-ufs (8.0G)
41943040 8388608 5 freebsd-ufs (4.0G)
50331648 85983215 6 freebsd-ufs (41G)
136314863 1 - free - (512B)
$ sudo gpart add -t mbr -i 2 -s 8G ada0
Password:
gpart: Invalid argument
$ sudo gpart add -t \!12 -i 2 -s 8G ada0
ada0s2 added
$
$ sudo newfs_msdos ada0s2
/dev/ada0s2: 16773056 sectors in 262079 FAT32 clusters (32768
bytes/cluster)
BytesPerSec=512 SecPerClust=64 ResSectors=32 FATs=2 Media=0xf0
SecPerTrack=63 Heads=16 HiddenSecs=0 HugeSectors=16777215 FATsecs=2048
RootCluster=2 FSInfo=1 Backup=2
$ sudo gpart add -t freebsd -i 3 -s 8G ada0
ada0s3 added
$ gpart show ada0
=> 63 976773105 ada0 MBR (465G)
63 136314864 1 freebsd [active] (65G)
136314927 16777215 2 !12 (8G)
153092142 16777215 3 freebsd (8G)
169869357 806903811 - free - (384G)
$ sudo newfs_msdos ada0s3
/dev/ada0s3: 16773056 sectors in 262079 FAT32 clusters (32768
bytes/cluster)
BytesPerSec=512 SecPerClust=64 ResSectors=32 FATs=2 Media=0xf0
SecPerTrack=63 Heads=16 HiddenSecs=0 HugeSectors=16777215 FATsecs=2048
RootCluster=2 FSInfo=1 Backup=2
$
this example show that, if you want a "msdos" or "fat32" partition, both
the type "\!12" or "freebsd" allows you to create a partition where you
could install a msdos filesystem (but the "mbr" does not).
Such behaviour is not surprising, (using freebsd-type to format as
msdos means you don't use the space allowed for labeling); but what is
really the purpose of the listed "mbr"-type in the gpart(8) manpage?
Cheers
Roger
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