Re: btrfs raid1 and btrfs raid10 arrays NOT REDUNDANT

[Jim Salter <jim@jrs-s.net>]

For anybody else interested, if you want your system to automatically 
boot a degraded btrfs array, here are my crib notes, verified working:

***************************** boot degraded

1. edit /etc/grub.d/10_linux, add degraded to the rootflags

     GRUB_CMDLINE_LINUX="rootflags=degraded,subvol=${rootsubvol} 
${GRUB_CMDLINE_LINUX}


2. add degraded to options in /etc/fstab also

UUID=bf9ea9b9-54a7-4efc-8003-6ac0b344c6b5 /               btrfs 
defaults,degraded,subvol=@       0       1


3. Update and reinstall GRUB to all boot disks

update-grub
grub-install /dev/vda
grub-install /dev/vdb

Now you have a system which will automatically start a degraded array.


******************************************************

Side note: sorry, but I absolutely don't buy the argument that "the 
system won't boot without you driving down to its physical location, 
standing in front of it, and hammering panickily at a BusyBox prompt" is 
the best way to find out your array is degraded.  I'll set up a Nagios 
module to check for degraded arrays using btrfs fi list instead, thanks...


On 01/03/2014 06:06 PM, Freddie Cash wrote:
> Why is manual intervention even needed?  Why isn't the filesystem 
> "smart" enough to mount in a degraded mode automatically?​
>
> -- 
> Freddie Cash
> fjwcash@gmail.com <mailto:fjwcash@gmail.com>