Re: btrfs raid1 and btrfs raid10 arrays NOT REDUNDANT

Joshua Schüler
2014-01-03T23:04:17Z

Am 03.01.2014 23:56, schrieb Jim Salter:
> I actually read the wiki pretty obsessively before blasting the list -
> could not successfully find anything answering the question, by scanning
> the FAQ or by Googling.
>
> You're right - mount -t btrfs -o degraded /dev/vdb /test worked fine.
don't forget to
btrfs device delete missing <path>
See
https://btrfs.wiki.kernel.org/index.php/Using_Btrfs_with_Multiple_Devices
>
> HOWEVER - this won't allow a root filesystem to mount. How do you deal
> with this if you'd set up a btrfs-raid1 or btrfs-raid10 as your root
> filesystem? Few things are scarier than seeing the "cannot find init"
> message in GRUB and being faced with a BusyBox prompt... which is
> actually how I initially got my scare; I was trying to do a walkthrough
> for setting up a raid1 / for an article in a major online magazine and
> it wouldn't boot at all after removing a device; I backed off and tested
> with a non root filesystem before hitting the list.
Add -o degraded to the boot-options in GRUB.

If your filesystem is more heavily corrupted then you either need the
btrfs tools in your initrd or a rescue cd
>
> I did find the -o degraded argument in the wiki now that you mentioned
> it - but it's not prominent enough if you ask me. =)
>
>

[snip]

Joshua