On Sat, Aug 20, 2016 at 9:21 AM, Chris Murphy <li...@colorremedies.com> wrote:
>If you > deleted this udev rule, you run the risk of some boots sometimes > having a slightly delayed drive becoming available and the volume > wrongly being mounted degraded when it's not necessary. Yuck. Revision time! If you were to delete this udev rule, it's possible to end up with an unnecessary degraded mount, simply due to a drive spinning up slower or otherwise having delayed readiness. Add on: Silently always mounting degraded in order to anticipate needing unattended degraded mounts will almost certainly lead to data loss. Btrfs just isn't ready for this yet. It has no concept of device faulty state still although patches for this are available for testing (not merged). So yeah, buyer beware. If you don't care about uptime and unattended operation, just self-healing during normal operation, then it's OK but you have to remain vigilant, and aware of Btrfs limitations, including it's lazy repair of formerly missing devices that reappear. It only fixes passively on reads. To completely fix it, you have to do a scrub, and you must do it before another drive goes missing or you can lose the whole file system. Btrfs has no partial resync like what's offered with mdadm arrays with a write-intent bitmap. -- Chris Murphy -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
