topic Re: max 4 partitions in Operating System - Linux

max 4 partitions

frangelico — Wed, 18 Dec 2002 23:39:05 GMT

Hi everybody,
I'm new in this forum.
I'll like to know why the MasterBootRecord accepts only a maximum of 4 partitions ?

Thanks !

Re: max 4 partitions

Kodjo Agbenu — Thu, 19 Dec 2002 00:29:02 GMT

Hi Frangelico,

This is a very old limitation of BIOS and Ms-DOS that was kept for compatibility reasons.

In fact, inside the 512 bytes of the Master Boot Record, the partition table is 16 bytes length, which means 4 bytes per partition descriptor.

To overcome this limitation while keeping compatibility, the concept of extended and logical partittions has been invented : 1 out of 4 partition can be configured as extended partition. Therefore, it serves as a second parition table that could poing to "logical" partitions.

The primary partitions are numbered 1..4.

One of these primary partitions can be set to be an extended partition.

Partitions over 5 are logical ones. They belong to the extended partition described above.

Good luck

Kodjo

Re: max 4 partitions

Chakravarthi — Thu, 19 Dec 2002 06:51:30 GMT

Hi,

Yes you can have Maximum 4 partitions, and allt he 4 can be primary or you can have 3 primary and one extended and the extended parition can be sub divided into n logical partitions,

for more info check the following link

http://www.techrescue.net/guides/prepdrv5.asp