# FreeBSD and DragonFlyBSD on same harddisk



## hwagemann (Oct 28, 2015)

Hello,

I want to compare FreeBSD and DragonFlyBSD. For installation of both systems I want to use my 128 GB ssd with GPT, starting with FreeBSD and then adding DragonFlyBSD. But how to prepare this disk? Would this work?

```
ada1p1 freebsd-boot 512 K
ada1p2 freebsd 50 G
ada1p3 df-boot 512 M
ada1p4 df 50 G
ada1p5 swap for both systems 8 G
```

I need further help, thanks in advance.

Kind regards,
  Holger


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## Oko (Oct 28, 2015)

hwagemann said:


> Hello,
> I want to compare FreeBSD and DragonFlyBSD. For installation of both systems I want to use my 128 GB ssd with GPT, starting with FreeBSD and then adding DragonFlyBSD. But how to prepare this disk?


I have never dual booted anything in my life so I would not know but reading the documentation and learning about how the boot process works on FreeBSD 

https://www.freebsd.org/doc/handbook/boot.html

and DF 

https://www.dragonflybsd.org/docs/newhandbook/Booting/

would be the start.  Some basic understanding of MBR v/s GPT and BIOS v/s UEFI is must. 

https://wiki.manjaro.org/index.php?title=Some_basics_of_MBR_v/s_GPT_and_BIOS_v/s_UEFI

A quick search of DF users mailing list

http://marc.info/?l=dragonfly-users&r=1&w=2

reveals that many people do dual boot DF with other OSs.


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## hwagemann (Oct 28, 2015)

Hello Oko,

thanks for your hints. In my case booting procedure is managed by grub2 of my arch installation, I'll add a further entry for DragonFlyBSD.

My question more refers to the partitions. Could I use a third partition of a harddisk as bsd-boot? In handbook I read about a max size of 512 K for freebsd-boot but no further restrictions, so I guess, it doesn't need first partition of a harddisk. I further guess, that swap can be shared.

Kind regards,
  Holger


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## garry (Oct 29, 2015)

hwagemann said:


> I want to compare FreeBSD and DragonFlyBSD. For installation of both systems I want to use my 128 GB ssd ....
> I need further help, thanks in advance.



I had a similar need to be able to boot either FreeBSD 10.2 or 11-CURRENT or NextBSD or ... other, but my system was already loaded with two SSDs (one with FreeBSD and one with Gentoo/Funtoo) and a zfs two-disk mirror (Western Digital Red NAS drives).  So I  made the boot drive physically swapable by puttting a hot swap drive bay in one of the 5.25-inch bays.  Of course this solution assumes a standard PC box, not a notebook computer.  Now I can completely swap the boot drive and allow each OS to have its own drive and its own boot loader and I can play around safely with alternate systems.

I don't know if such a solution is even possible for your hardware but ... it works for me.


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## hwagemann (Oct 30, 2015)

garry said:


> I had a similar need to be able to boot either FreeBSD 10.2 or 11-CURRENT or NextBSD or ... other, but my system was already loaded with two SSDs (one with FreeBSD and one with Gentoo/Funtoo) and a zfs two-disk mirror (Western Digital Red NAS drives).  So I  made the boot drive physically swapable by puttting a hot swap drive bay in one of the 5.25-inch bays.  Of course this solution assumes a standard PC box, not a notebook computer.  Now I can completely swap the boot drive and allow each OS to have its own drive and its own boot loader and I can play around safely with alternate systems.
> 
> I don't know if such a solution is even possible for your hardware but ... it works for me.


Hey garry,

thanks for your hints. The harddrive constallation on my computer is following:

```
/dev/sda with GPT 256 GB
/dev/sda1    Arch Linux
/dev/sda2    Debian GNU/Linux
/dev/sda3    siduction
/dev/sda4    linux-swap
/dev/sdax    place for further Linux Distributions
/dev/sda128 bios_grub

/dev/ada1  with GPT 128 GB
/dev/ada1p1  freebsd-boot
/dev/ada1p2  freebsd
/dev/ada1p3  freebsd-swap

/dev/sdc with GPT 1 TB
/dev/sdc1 ext2 shared data for Linux and FreeBSD
```

FreeBSD start is managed by grub2 of Arch Linux. I want to prepair /dev/ada1 for a new installation of FreeBSD and want to add DragonFlyBSD. I don't want to modify stuff on first and third harddisk, apart from a further entry in /boot/grub.cfg  for my new DragonFlyBSD installation.

I'll test following:

```
ada1p1 freebsd-boot 512 K
ada1p2 freebsd 50 G
ada1p3 df-boot 512 M
ada1p4 df 50 G
ada1p5 swap for both systems 8 G
```

I've made a short test with df on my notebook, comparing with partitioning of FreeBSD there I've seen another kind of partitioning:

```
ada0p1
ada0p1a
ada0p1b
ada0p1c
```

Hmm, could somebody explain this?

Kind regards,
  Holger


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## chrbr (Oct 30, 2015)

Dear hwagemann,
when I have started using FreeBSD I have had a single disk with 1x Linux and grub and 2x FreeBSD Installations using the MBR partitioning scheme.
The notation as ada0p1a seems to be as a FreeBSD partition in the slice ada0p1. Unfortunately the FreeBSD slice is named as partition in other context as under Windows or Linux. This can be somehow confusing.
Please see https://www.freebsd.org/doc/en_US.I...disk-organization.html#basics-disk-slice-part for details.


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## wblock@ (Oct 31, 2015)

Short version: use GPT, avoid MBR.

Longer version:
MBR is the old partitioning method, allowing only four "slices" on a drive (s is for "slice" on FreeBSD).  FreeBSD's even older and superior disklabel partitioning allowed many more partitions on a disk, each using a letter, and so the idea was hit upon to put FreeBSD partitions inside an MBR slice, providing the worst of both worlds: https://www.freebsd.org/doc/en_US.I...k-organization.html#basics-concept-disk-model.

GPT allows many partitions on a drive, up to 128 by default.  On FreeBSD, these partitions are represented by a p.  Because there is no need to put FreeBSD partitions inside a single GPT partition, it simplifies things.  It is possible, but I have not seen anyone do it yet.  There is no point.

I do not know what DragonFly does for device names.  On FreeBSD, ada0p1a would be from that pointless combination of GPT and FreeBSD disklabel.


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## sidetone (Dec 7, 2015)

BSD partitions now just use letter names. Maybe it's bsd64 partitions, since it's hard to find documentation on it. I used it and my drives are numbered: 
	
	



```
ada0a
ada0b
ada0d
```
 It skips ada0c, because it's reserved for some reason. It allows more real partitions than 4, but it still has a limit.


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## wblock@ (Dec 7, 2015)

bsdlabel(8) partitions have always used letters.  If there is no p or s before them, it means the disk only has BSDlabel partitioning.  That is unknown outside of the BSD world, and called "dangerously dedicated".

The c partition represents the whole disk.  The only reason to use BSDlabel partitioning is when GPT cannot be used for some reason.


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## hwagemann (Dec 8, 2015)

Hello,

thanks for your explanation.

Just as reminder: I've not forgotten my promise to write something about installing FreeBSD as desktop system for beginners. But I need some more time for it.

Kind regards,
  Holger


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## mirco (Jul 7, 2016)

hwagemann said:


> FreeBSD start is managed by grub2 of Arch Linux. I want to prepair /dev/ada1 for a new installation of FreeBSD and want to add DragonFlyBSD.



Did you manage booting DF with grub2?
If yes, how?


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