Reinstall without reformat

Warren Block wblock at
Mon Oct 14 13:51:21 UTC 2013

On Mon, 14 Oct 2013, Polytropon wrote:

> On Sun, 13 Oct 2013 23:01:02 -0600 (MDT), Warren Block wrote:
>> On Mon, 14 Oct 2013, Polytropon wrote:
>>> On Sun, 13 Oct 2013 13:24:30 -0400, Kenta Suzumoto wrote:
>>>> Hi all. Is it possible to install FreeBSD without formatting the disk?
>>> Yes. The installer supports not formatting existing partitions.
>>> The file system characteristica will be kept, possible content
>>> will overwritten. Note that "superfluous content" will also be
>>> kept, except of course you previously remove everything.
>> sysinstall supported that, but AFAIK bsdinstall does not.
> Oh, seems you're right. I've checked The FreeBSD Handbook for
> the relevant instructions for using bsdinstall at
> and
> and I didn't find an option to _not_ initialize existing partitions,
> even though it seems you can assign existing partitions without any
> problem. The remaining question: Will they be initialized again?

It is possible to mount filesystems manually from the shell and have 
bsdinstall continue with the install without formatting them.  It's been 
a while since I tried that, and I don't recall the exact details. 
bsdinstall(8) suggests it may be as easy as just having the existing 
filesystems mounted at /mnt.  Still, not something to try without a 

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