Re: RAID 1 with no data on it when accidentally switched HDD

Chris Murphy
2014-01-12T21:50:05Z

On Jan 12, 2014, at 2:40 PM, Ingo Ebel <ingo.ebel@ingoebel.de> wrote:

> Hi,
>
>> I don't understand the exact sequence. How does a 3rd drive appear as sdc when
>> the 2nd drive is sdc and sdc1 is part of a Btrfs file system already? Did you
>> reboot and the 3rd drive became sdc? This needs to be explained better,
>> including the exact commands you used.
>
> Ok i try to.
>
> I made the btrfs with:
> mkfs.btrfs -f -m raid1 -d raid1 /dev/sdb1 /dev/sdc1
>
> part of my /etc/fstab:
>
> /dev/sdb1 /data btrfs defaults,compress 0 0
> /dev/sdb1 /usr/src/packages btrfs defaults,compress,subvol=packages 0 0
>
> No other special commands used.
>
> Hardware Setup:
>
> SATA-Port 1 - HDD with opensuse
> SATA-Port 2 - HDD /dev/sdb
> SATA-Port 3 - DVD
> SATA-Port 4 - HDD /dev/sdc
>
> Put at SATA Port 3 an HDD instead an DVD and it got /dev/sdc after rebooting my system.

The drives on SATA port 2 and 4 are designated as what block devices after the reboot?

This change in block device designation is why using /dev/X in fstab is not a good idea, it's an ambiguous entry. I don't know what file system was actually mounted by fstab, and to what volume sdc was added. I suggest changing fstab to use fs UUID from blkid.

In the meantime what do you get for :
btrfs fi show
cat /proc/self/mountinfo | grep btrfs

Chris Murphy