What is the recommended size for a linux /boot partition?

Question

What is the recommended size for a linux /boot partition?

And is it safe to not have a /boot partition?

I see some servers don't have a /boot partition while some servers have a 128M /boot partition. I am a little confused. Is /boot partition necessary? If it is, how large should it be?

Answer 1

These days, 100 Megabytes or 200 Megabytes is the norm.

You do not need to have a /boot partition. However, it's good to have for flexibility reasons (LVM, encryption, BIOS limitations).

Also see: http://superuser.com/questions/66015/installing-ubuntu-do-i-really-need-a-boot-parition

Answer 2

What is the recommended size for a linux /boot partition?

The /boot parition contains the GRUB configuration, the kernel with their System.map, ... I think ~ 100MB is enough.

And is it safe to not have a /boot partition?

Yes. But a separate /boot partition has some advantages:

• as a rescue partition
• rootfs is on a LVM, RAID, is encrypted, or unsupported by GRUB
• may be saves a few seconds of boot time
• ...

Answer 3

I tend to create a 1GB /boot. I leave a livecd image which has various repair tools in my /boot. I mostly do this for systems that at the remote sites I support. With the right configuration, and enough memory, grub2 can boot the image without extracting the contents. A couple times I have talked remote staff into rebooting the system to the livecd image and starting networking/ssh on a system that was having issues so I could connect and repair things.

This certainly isn't required, or even common.

Answer 4

It also differs distribution from distribution. For example for Fedora minimum is 250MB[1] and 500MB is default and if you plan to (pre)upgrade in the future 500MB is required[2]. If space is not a problem I would go for 1GB to prevent shuffling partitions later as I had to do when upgrading recently.

[1] http://docs.fedoraproject.org/en-US/Fedora/16/html/Installation_Guide/s2-diskpartrecommend-x86.html [2] http://fedoraproject.org/wiki/How_to_use_PreUpgrade#Not_enough_space_in_.2Fboot

Answer 5

It's mostly a function of how many kernels you have installed, and the size of their initrds.

For a 3.0 series kernel, initrd runs about 13 MB. For early 2.6 kernels, this was 3.4 MB. So, if you plan on keeping more than a few kernels around, you'll need at least a couple hundred MB.

How much and whether or not this applies to you depends on your use case. If you multi-boot, test kernels, and/or upgrade frequently, you could run out of space on a 100 MB /boot partition quickly. If you don't do any of these things, it's probably going to be sufficient.

There are very few reasons to skimp on storage (it's cheap, BIOS, mount, and bootloader restrictions on blocks are mostly a thing of the past), and I'm seeing a marked growth in kernel resources with time, so the safe bet would be ~250 MB - 1 GB for now. I still generally prefer a separate /boot partition for control and isolation, though this has almost entirely become a matter of taste (RAID devices would be one obvious exception, LVM and encryption as well as noted by others).

Answer 6

I always use 100MB as a rule when I'm building systems. I suppose if you're going to be testing out tons of different kernels (or building your own custom kernels) you may want a larger one, but 100MB is enough for most people. Also, as mentioned, having a separate boot partition is a good idea for a bunch of reasons.