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I will be installing Ubuntu 9.10.

However, when I go to the advanced options for making the partitions. I have decided that I will create a

swap file x2 size of RAM / (root) partition.

I have read some documents that say you should also create a boot partition (primary partition) for the first partition so that the BIOS can easily find it. And allocate only about 100MB.

I am just wondering do I need to create a boot partition? And what does it really do?

Many thanks,

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This is a dupe. You'll find the answers here: – innaM Nov 5 '09 at 9:36
This question doesn't strike me as a duplicate. – DaveParillo Feb 8 '10 at 21:07
up vote 5 down vote accepted

It's a choice. You might, or you might not. I typically do. Besides swap, I typically create 3 partitions:

  1. /boot - typically 60MB or so. More for fedora, or if I plan to experiment / have several kernels installed
  2. / - 7 or 8 GB to hold everything else that's not /home
  3. /home - the rest of my disk.

The main reason I split to out like this is to give me as many options as possible during recovery and backup situations. If things never go wrong, 1 big partition will work and you may never have to care.

Maybe I'm just old and paranoid ;-)

If you are concerned about security, after installation, you can set your boot partition to be read only. This prevents anyone (even you) from writing anything to your kernel. While fairly secure, it does mean that when those old Kernel updates show up in your update window, they will fail to install until you make your boot partition writable, reboot, then install them. I have done this on my daughters laptop, just as an added layer against anything tampering with her kernel - she can install software, but to mod her kernel, she has to ask me for help. It give me a chance to verify this is something that really should be installed to begin with.

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Hello, thanks for your help. I am just wondering The boot would be a primary partition. / root and /home would be logical partitions? Thanks. – ant2009 Nov 5 '09 at 6:23
They should all be logical partitions. IMO. – CarlF Nov 5 '09 at 7:16
I set my boot partition as a primary partition, not a logical partition. Again, this in case of disaster, but it is not technically necessary. Ubuntu has a good article explaining the basics of partitioning. – DaveParillo Nov 5 '09 at 15:11
What if you have multiple disks? Where should the boot partition be on? sda? sdb2? Or is there a way to mirror the boot partition, and if so, is it a good idea? – CMCDragonkai Jun 29 '14 at 9:51

In general, you can just use one partition for everything. Historically, many systems used different partitions for different parts of the system, but this is no longer necessary.

There are still some special situations where you need more than one partition:

  • You need a separate /boot partition if you want to use full disk encryption (e.g. LUKS or Truecrypt), because you need something to boot from :-).

  • If you dual-boot and want to be able to read files from both systems, they'll need to be on a filesystem that both systems can read. So it might make sense to have e.g. a multimedia partition with NTFS or VFAT if you dual-boot Linux and Windows, so both can use the files.

  • If you use full disk encryption, there is a noticeable overhead for reading and writing very large files (e.g. videos). You might want to have a separate unencrypted partition for those.

  • If you plan on re-partitioning or installing other OS from time to time, it's easier if you have a /boot at the beginning of the disk as number one (e.g. /dev/sda1) so as to avoid breaking grub.

There are also some obsolete reasons. You may read about them in old documentation, but they no longer apply to current systems:

  • On some old hardware a boot partition is necessary because of BIOS limitations (e.g. unable to boot from a partition beyound 1024 cylinders). I believe this only applies to very old systems however (more than ~5-10 years old).

  • On old Linux versions (V2.2, maybe 2.4) a swap partition was faster than a swap file, so having a swap partition was advisable. On Linux 2.6, both should give equivalent performance ( ).

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There is no need to create a boot partition. Everything but swap can go on one partition without causing any problems. Even swap can be on the single partition (in the form of a swap file) but swap files are somewhat slower than swap partitions.

Advice about creating multiple partitions has nothing to do with the BIOS finding them (which is bogus). It's about such things as sharing a single /home/yourname partition between multiple operating systems, and making certain types of backups easier. For most users a single partition is the easiest to set up and works fine.

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