Re: My system mounts the wrong btrfs partition, from the wrong disk!
From: Goffredo Baroncelli <hidden>
Date: 2016-11-26 13:24:46
On 2016-11-26 00:56, Chris Murphy wrote:
On Fri, Nov 25, 2016 at 4:17 AM, Roman Mamedov [off-list ref] wrote:quoted
On Fri, 25 Nov 2016 12:05:57 +0100 Niccolò Belli [off-list ref] wrote:quoted
This is something pretty unbelievable, so I had to repeat it several times before finding the courage to actually post it to the mailing list :) After dozens of data loss I don't trust my btrfs partition that much, so I make a backup copy with dd weekly.https://btrfs.wiki.kernel.org/index.php/Gotchas#Block-level_copies_of_devices "don't make copies with dd."Yeah. In the user's defense, it's way overdue for the kernel to refuse to mount without some override flag like XFS does. This behavior is just plain user hostile right now, and Btrfs gets an extra ding because it's supposed to be better: easier to admin and have better data integrity. Basically this is Btrfs eating at least one, possibly both, file systems at the same time without warning, and it's not good enough to warn in the wiki.
When I read these "incidents" on the ML, I still think that the actual BTRFS way to handling the devices discovery is overcomplicated and not reliable: currently udev push back the device in the kernel which manages an own list of btrfs devices. Then the mount command suggests the kernel to mount a filesystem on the basis of the UUID. In case of problem nor udev nor mount are capable to print any useful message and/or suggestion. Even in case of UUID conflicts (which could be very simple to handle) this system is unreliable. In the past I developed a mount.btrfs helper which took care of devices discovery and also of these checks; also it could be a place where develop the handling of incomplete multi-disks filesystem.... I hope that sooner or later someone rethink about that. http://www.spinics.net/lists/linux-btrfs/msg39706.html BR G.Baroncelli -- gpg @keyserver.linux.it: Goffredo Baroncelli <kreijackATinwind.it> Key fingerprint BBF5 1610 0B64 DAC6 5F7D 17B2 0EDA 9B37 8B82 E0B5