[Android General] NYLimited:
There is apparently a lot of information floating around on the topic of "partition types". While they are fairly well defined and documented I could find nothing specific about requiring or recommending FAT32 type "b" partitions for Android. That does not mean I could not have missed the info but one would think it should be quite easy to find if this was a blanket requirement.

I read through Tytung's git repositories (okay, kinda speed reading since there is way too much source code there for limited time reading) and I could not find any restrictions on FAT32 type, though again, admittedly I could have missed it.

As importantly, I created a FAT32 partition as type "b" on one card and another as type "c" on another card - they both worked equally well for me. Minitool Partition Wizard creates type "c" (the FAT32 default for the program) unless you change it yourself. I have apparently never used anything other than type "c" on my HD2, on Typhoon GB ROMs, and Tytung's ICS and JB ROMs. So, you got me. If it matters I have not seen that yet.

Briefly, the partition type (or partition ID) in a partition's entry in the partition table inside a Master Boot Record (MBR) is a byte value intended to specify the file system the partition contains and/or to flag special access methods used to access these partitions, such as CHS (Cylinder/Head/Sector) mappings, LBA (Logical Block Addressing) access, logical mapped geometries, special driver access, hidden partitions, secured or encrypted filesystems, etc.

It is up to an operating system's boot loader and/or kernel how to interpret the value.

Type "b" was the original (or older) WIN95 OSR2 FAT32 design. It is limited to partition sizes of 2047GB or less and it depended on the BIOS INT 13 of those PCs. Type "c" also dates back to WIN95 OSR2 FAT32 but is LBA-mapped and is considered an extended-INT 13 equivalent of 0b. Of course, both of these specs were designed for actual (hard) disk drives. According to some notes I have seen the "c" revision should be faster but there is no concrete evidence of this as far as I have seen.

By changing the partition type ID, users can prevent the system from using or initializing partitions - this is up to the operating system which will be accessing it.

According to Microsoft the following limitations exist

using the FAT32 file system with Windows

operating systems:

Clusters cannot be 64 kilobytes (KB) or larger. If clusters were 64 KB or larger, some programs (such as Setup programs) might calculate disk space incorrectly.

A volume must contain at least 65,527 clusters to use the FAT32 file system. You cannot increase the cluster size on a volume using the FAT32 file system so that it ends up with less than 65,527 clusters.

The maximum possible number of clusters on a volume using the FAT32 file system is 268,435,445. With a maximum of 32 KB per cluster with space for the file allocation table (FAT), this equates to a maximum disk size of approximately 8 terabytes (TB).

The ScanDisk tool included with Microsoft Windows 95 and Microsoft Windows 98 is a 16-bit program. Such programs have a single memory block maximum allocation size of 16 MB less 64 KB. Therefore, The Windows 95 or Windows 98 ScanDisk tool cannot process volumes using the FAT32 file system that have a FAT larger than 16 MB less 64 KB in size. A FAT entry on a volume using the FAT32 file system uses 4 bytes, so ScanDisk cannot process the FAT on a volume using the FAT32 file system that defines more than 4,177,920 clusters (including the two reserved clusters). Including the FATs themselves, this works out, at the maximum of 32 KB per cluster, to a volume size of 127.53 gigabytes (GB).

You cannot decrease the cluster size on a volume using the FAT32 file system so that the FAT ends up larger than 16 MB less 64 KB in size.

You cannot format a volume larger than 32 GB in size using the FAT32 file system in Windows 2000. The Windows 2000 FastFAT driver can mount and support volumes larger than 32 GB that use the FAT32 file system (subject to the other limits), but you cannot create one using the Format tool. This behavior is by design. If you need to create a volume larger than 32 GB, use the NTFS file system instead.

Keep in mind the above is Windows (Microsoft). Linux and Android handle things a little differently. All of the Linux filesystem drivers support all three FAT types, namely FAT12, FAT16 and FAT32. As far as I know Android should handle them the same way. Other common features that they all support are various Linux mounting options (specified with the -o option to the mount command), such as "uid", "gid", "umask", etc.

There really is so much more to partitioning and formatting that I simply cannot cover it all here, however, all the information is already available someplace on the internet. Search is a wonderful tool, everyone! :)