How to copy freenas-boot pool onto a usb drive and boot from it?

[seltz]

Out of curiosity, I'm trying to see if it's possible to copy of my freenas boot partition (currently on an ssd) onto a smaller usb drive then boot off it but ran into issues when booting (see results below) - any idea? I realize this isn't a normal use case and the general recommendation is to do mirroring.



Here's my process
:


#usb drive - wipe contents
gpart destroy -F /dev/da0
#usb drive - setup gpt partitioning scheme
gpart create -s gpt da0
#usb drive - setup boot partition
gpart add -b 40 -s 512k -t freebsd-boot da1
#usb drive - add boot partition
gpart add -t freebsd-zfs -l root da0


# usb drive: embed bootstrap code in partion scheme metadata
gpart bootcode -b /boot/pmbr -p /boot/gptzfsboot -i 1 da0


#so now da0p1 has the bootcode, da0p2 has open space for root


# First attempt to just to do a mirror, you quickly
# realize you can’t do it with a small usb drive
# zpool attach freenas-boot /dev/ada0p2 /dev/da0p2
# > cannot attach /dev/da0p2 to /dev/ada0p2: device is too small
# So let’s try sending a snapshot


#usb drive: create zpool
zpool create freenas-boot2 /dev/da0p2


#current boot drive: create snapshot
zfs snapshot freenas-boot/ROOT@migrate


#current boot drive -> usb drive:
zfs send -R freenas-boot@migrate | zfs recv -Fdu freenas-boot2
zpool list #notice the other drive has copied contents now


Attempt to reboot, and boot off the flash drive instead.

I have tried rebooting (back on the regular ssd) and observing that the usb drive seems to be having some space occupied:

freenas-boot 95.5G 1.01G 94.5G - - 0% 1% 1.00x ONLINE -
freenas-boot2 7G 1.27G 5.73G - - 0% 18% 1.00x ONLINE -

Though after trying to mount (not sure I should be doing this) the filesystem it's empty. Did I mess up in sending the snapshot? I'm Assuming snapshots can be sent while the source volume is mounted.

 

[sretalla]

Don't do that.

Just save your config, install fresh to the USB stick and restore the config.

(USB sticks are no longer the recommended boot option... better to use a USB to SATA and SSD if you want to have trouble-free NAS operation).

 

[seltz]

Don't do that.

Just save your config, install fresh to the USB stick and restore the config.

(USB sticks are no longer the recommended boot option... better to use a USB to SATA and SSD if you want to have trouble-free NAS operation).

I'm trying to see what's possible rather than what one should do. I do understand the normal recommendation is to do a fresh install, use an entire disk for freenas-boot, etc. There are people who have successfully managed to mirror freenas-boot then boot off it.

 

[sretalla]

I don't think there is ever a good reason to do that.

The trick will probably be marking the partition as active/bootable (fdisk)

 

[Patrick M. Hausen]

I did it with mirroring, but you need a drive the same size or larger for that.
I doubt you can get it to boot as long as the pool is not called "freenas-boot". Which you cannot create a second time from a running FreeNAS.
Hence attach -> mirror -> resilver -> detach old drive.

 

[seltz]

I did it with mirroring, but you need a drive the same size or larger for that.
I doubt you can get it to boot as long as the pool is not called "FreeNAS-boot". Which you cannot create a second time from a running FreeNAS.
Hence attach -> mirror -> resilver -> detach old drive.

Thanks. Ended up following this path and it worked! Documented it in https://www.ixsystems.com/community...itioned-single-ssd-with-boot-and-jails.85867/