# ZFS mount root error



## dkline201 (Feb 27, 2018)

I created a FreeBSD 10.3 ZFS boot drive on a non-RAIDed system,  and then tried to move that drive to a DELL R740xd with PERC H730 RAID board.  (for compatibility purposes,  I cannot rebuild this R740 with 10.3,  or upgrade to 11.1 YET)

After configuring the drive as a RAID0 (one drive), the system booted to a "mount root error",  which I have seen before, but never found a solution without rebuilding.

This time I tried putting the same drive into a DELL R730xd which also uses the same PERC H730 RAID board,  and it asked me to import the Foreign Config which it got from the R740xd.  I imported it, and the system booted properly.

I then put that same drive back into the R740xd,  and it asked again about the Foreign Config.  I tried importing, but that failed, so I deleted the Foreign Config.  I then had to Clear ALL Config,  and reconfigure as the RAID0 (one drive). 

That worked this time,  and the system booted properly.  So the question here is "why"?  I know it has to do with the build on non-RAID and then installing into a RAIDed system.  But from what I have read on these forums, no one has been able to come up with an easier solution around the "mount root error".

Thanks for taking the time to read this.  I hope there will be some answers.


----------



## SirDice (Feb 27, 2018)

dkline201 said:


> After configuring the drive as a RAID0 (one drive), the system booted to a "mount root error", which I have seen before, but never found a solution without rebuilding.


The problem with this is that a lot of RAID cards write information on disk for that. Which usually means it's overwriting the original ZFS information. 



dkline201 said:


> So the question here is "why"? I know it has to do with the build on non-RAID and then installing into a RAIDed system.


The RAID BIOS typically writes this information to the disk, a non-RAID BIOS doesn't. 

Some (newer) RAID cards nowadays have an option to select one or all disks as JBOD. That's always preferred over a single disk RAID0.


----------

