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ZFS mount root error

dkline201

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Messages: 15

#1
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

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#2
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.

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.
 
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