Is it possible to create ZFS tank on USB media ?

[David Christensen]

On 04/17/2017 12:34 PM, Manish Jain wrote:
> Being new to ZFS, I wonder if is possible to create ZFS root on
> removable media like a USB pen drive ?

One of my favorite tricks is to use the Debian GNU/Linux installer to 
install to a (BIOS, MBR) 16 GB USB 3.0 flash drive -- for use as a 
poor-man's SSD for low-end machines, as a "portable" desktop, as a 
"rescue/repair/test" live image, etc.  I have a couple USB flash drives 
with Debian 7; I need to try it with Debian 8.


It's been a couple of years since I tried installing FreeBSD onto a USB 
flash drive using the FreeBSD installer.  The last time I tried, 
apparently such was not supported.  Various readers of this mailing list 
suggested various techniques for installing by hand, but I was then, and 
still would be now, looking for an OOTB KISS solution.


> Logically, it sounds pretty cool - and a convenient way of migrating
> with just a single MBR slice available :
>
> a) create a ZFS tank on USB
> b) rsync your installation to ztank
> c) boot from USB
> d) create a second tank : this time on the slice that originally was UFS
> e) rsync ztank to ztank2
>
> Is that too weird ? Impossible ? Thanks for shedding any light.

I don't know enough FreeBSD or ZFS to comment.


> (As already mentioned in a post I just made to f-q, my MBR slice index
> corruption has been taken care of - by - of all people - Microsoft,  : - )
>
> I used Windows to create a new slice, a Windows reshuffled the slice
> indexes to pack them in the normal order).

I still prefer and recommend one OS per system disk.  The USB flash 
drive trick is ideal for computers with space for only one drive, such 
as laptops.


David