Understanding Logical, Primary, and Extended Partitions

[johntkucz]

This is from a blog post I am doing. The questions are at the bottom

<strong>A Word on Primary/Extended/Logical Partitions
</strong>The difference between primary, extended, and logical partitions, to say the least, greatly confused me. Here's what you need to know. When you partition a drive you have the option of choosing the new partition to be primary or extended.

Primary partitions are partitions
<ol>
<li>from which you can boot an OS</li>
<li> automatically get assigned to a device location</li>
<li> partitioning them must involve the assignment of a filesystem (ntfs, ext4, FAT32, and the like)</li>
<li>have a maximum number of 4 (you can only have 4 primary partitions on any given single hard disk)</li>

Extended partitions
<li>have unlimited count per hard disk (there's no 4 maximum, like with primary partitions)</li>
<li>do not get automatically assigned a device location (nor drive letter in windows)</li>
<li>do NOT get formatted with a filesystem (filesystems are assigned later)</li></ol>

Here's a very helpful diagram from gparted.


"IMAGE of parittions


Now I made this overly complicated to illustrate the different partitioning types:

<ol>
<li>Partition 1, NTFS, Primary, 300GB,<strong> 1/4 Primary</strong>
</li>
<li>Partition 2, NTFS, Primary, 200GB,<strong> 2/4 Primary</strong>
</li>
<li>Partition 3 (called #5 in diagram), No filesystem, Extended, 300GB, (NOTE: Takes the Place of a primary partition! <strong>Counts as 3/4 primary partition)!</strong>
</li>
<ol>
<li>Partition3-1 (called Partition #6), Logical Partition of partition 3 (the extended partition), 29.29GB, ext2
</li>
<li>Partition3-1 (called partition #7 in gparted, idiotically), Logical partition of Partition 3, NTFS, 39.06GB
</li>
<li>Partition3-3 (called partition # 8), Logical Partition of Partition 3), 97.65GB, linux-swap (it would be idiotic to make the swap partition larger than the linux ext2/3/4 partition but this is just illustrative of primary, extended, and logical partitions.
</li>
<li>Partition3-4 (called partition #9), Logical partition of Partition 3, NTFS, 134GB.
</li>
</ol>
<li>Partition 4 (actually called partition #4 in gparted), ext4, 100GB, <strong>Primary Partition 4/4</strong>
</li>

</ol>

QUESTIONS


AFAIK, This partitioning scheme has 3 bootable partitions (the three primaries), 1 extended and 4 logical parititions within that one extended partition. Is it true that if you use an extended partition, it (nor any of its logical partitions can be booted from)?
What about linux-swap. I couldn't do an extended partition and make one logical ext4 and the other logical linux-swap? So using linux ext4 (primary) and linux-swap (primary) would take up two of the four primary parititions?

 

[johntkucz]

Basically, the
TL;DR
is
if I do linux (ext4) (must be primary for it to be bootable with linux os, right?)
and a swap. Doesn't the swap have to be primary, too? How could it not?

I liked the idea of doing ONE extended with an ext4 and a linux-swap as two logical partitions within the extended, but then the ext4 with linux os couldn't boot??


BASICALLY: If you make an extended partition, (can one of those logical partitions be used as linux swap)? AND NONE of those logical partitions (nor the extended) one can boot from, correct??

This is slightly irksome and the 4 primary partition limit seems unnecessary.


(please don't bother responding if you've never worked with these three types of partitions)