Suddenly "BTX halted" on boot

Andrea Venturoli ml at
Fri Jul 20 07:04:41 UTC 2018


I've got a server which has been working for years; this morning I 
rebooted it and it wouldn't come up (showing the message in subject).

Luckily, this is a ZFS RAID1 setup, so entering the BIOS and choosing to 
boot from the other HD got me up and running.

I don't have any idea how this could have happened, smartctl says both 
disks are good and I've never seen errors in the logs. "zpool status" 
also says everything is fine.

# gpart show /dev/ada0
=>        40  1953525088  ada0  GPT  (932G)
           40        1024     1  freebsd-boot  (512K)
         1064    67108864     2  freebsd-swap  (32G)
     67109928  1886415192     3  freebsd-zfs  (900G)
   1953525120           8        - free -  (4.0K)

Same for ada1.

I believe I should solve, by issuing the following command:
gpart bootcode -b /boot/pmbr -p /boot/gptzfsboot -i 1 ada1

However I thought I'd ask for confirmation before screwing everything.
I guess ada0 is always where I'm currently booting from, right?

Of course I have dumps and backups, but I'd rather not need to use them 
this time :)

  bye & Thanks

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