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PRIMARY, EXTENDED and LOGICAL PARTITIONS


There is always a lot of confusion about partitions and partition numbers. So let us try to shed some light:

On an IDE drive, the first drive is called hda, and the partitions are shown as hda1, hda2 . . . . etc. etc. Your second drive is called hdb.

On a SCSI drive, the first drive is called sda, the partitions are sda1, sda2 . . The second drive is called sdb.

Now that was relatively simple, but now comes the more complicated part, I took parts of this from a post of Jason Wallwork ( Linuxdude32 ) because he was able to explain it better then I can:

QUOTE (Jason @ Forum 2004)
An extended partition is the only kind of partition that can have multiple partitions inside. Think of it like a box that contains other boxes, the logical partitions. The extended partition can't store anything, it's just a holder for logical partitions.
The extended partitions is a way to get around the fact you can only have four primary partitions on a drive. You can put lots of logical partitions inside it.

hda is the whole drive
hda1 is a primary partition
hda2 is a primary partition
hda4 is an extended partition
hda5 is an logical partition
hda6 is an logical partition

You will never see hda4 mounted, just hda5 and hda6, in this case. Note that Linux numbers primary partitions 1-4, logical partitions start at 5 and up, even if there are less than 4 primary partitions.


NOTE: On an IDE drive you can have up to 63 partitions, 3 primary and 60 logical ( contained in one extended partition )
On a SCSI drive the maximum number of partitions is 15

So, in a nutshell: if you start out with one HD that has windows C: and D: You will see them in Linux as hda1 and hda2 . . . then as you add a distro and let it automatically use the free space on that drive ( if that distro has that option like Mandrake ) it will make an extended partition and set up a partition for / and a partition for /swap plus a /home partition and call them hda5, hda6 and hda7 ( in that order ). You will see that if you make the partitions yourself, using preferably a Linux tool to make the partitions, the result will be more or less the same, only in that case you will be able to make even more partitions . . . for extra storage, backups, or additional distros.
You will only need one swap partition as that can be shared by the various distros.


Bruno


-- Sep 2 2004 ( Revised Dec 12 2005 ) --


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