# Documentation for /boot/zfsboot?



## Kringel (Jun 20, 2012)

Hi,

*I* am about to follow this guide to install FreeBSD with ZFS root inside a MBR slice. But after reading the instructions *I* started to wonder on how step 10 works:

[CMD=""]dd if=/mnt2/boot/zfsboot of=/dev/ad0s3 count=1[/CMD]

Writes the first the first 512 Bytes of zfsboot to the start of the slice. Ok. But now:

[CMD=""]dd if=/mnt2/boot/zfsboot of=/dev/ad0s3a skip=1 seek=1024[/CMD]

Writes the rest of zfsboot inside the slice, but starting to write at a offset of 512kB.

The _Section 1.4: Boot Block_ of the ZFS specification says that 3.5MB of reserved space are at this position. This explains why the 64k of zfsboot fit in there without bothering the filesystem.

I guess the first block will load the rest of the code from that position when it is executed during the boot process. But I don*'*t like to blindly follow the linked wiki article.

So here is my question: Is there any documentation for /boot/zfsboot? I mean without the wiki article *I* would have no idea on how to use it. There seems to be no no man page mentioning it. And searching the net was also without luck.


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## trutlze (Sep 19, 2012)

I would be interested in this too, as I am facing problems installing FreeBSD 9.0 in a ZFS inside MBR partition scheme next to Windows 7.

I followed the guide you pointed out and it doesn't work. One problem is (solved for me) that the guide is not written for FreeBSD 9.x. You can't install FreeBSD as you would do with previous versions because the installer and directory structure has changed.

I found some hints by Doug Rabson on zfsboot here, but they're from 2009. Something might have changed since then ... And obviously it's no documentation.


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## wblock@ (Sep 19, 2012)

trutlze said:
			
		

> I would be interested in this too, as I am facing problems installing FreeBSD 9.0 in a ZFS inside MBR partition scheme next to Windows 7.
> 
> I followed the guide you pointed out and it doesn't work. One problem is (solved for me) that the guide is not written for FreeBSD 9.x. You can't install FreeBSD as you would do with previous versions because the installer and directory structure has changed.



The installer is different, but the directory structure is the same.  What caused problems?


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## trutlze (Sep 19, 2012)

wblock@ said:
			
		

> The installer is different, but the directory structure is the same.  What caused problems?



The guide shows how to manually install FreeBSD by using install.sh-scripts. With FreeBSD 9.x there are txz-packages in another directory and you'll have to untar them ... I didn't mean the directory structure of the installed system, but of the installation system.

But I think this hasn't to do anything with the main topic of this thread.


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