George Chlipala posted on Tue, 25 Oct 2016 09:30:34 -0500 as excerpted: > We had a major failure in one drive in a RAID56 BTRFS volume and that > drive is no longer accessible. How can I replace the drive without > mounting the filesystem? I have tried using a degraded mount but I > receive the following error messages Someone should be along with specific help, but FYI, btrfs raid56 mode is bugged at this time and may require a major rewrite to fix properly. As a result it's not recommended for anything but testing, and due to immaturity of the raid56 code, deployment with backups ready or otherwise with data that can be lost has always been the very strong recommendation even before these specific bugs were known. That being the case and since switching to other than raid56 mode is strongly recommended anyway, blowing away the existing filesystem and recreating in raid1 or raid10 mode, then restoring from backups if the data was worth the trouble of having them, is the shortest and most efficient way back to operation. Saving the data on the raid56 may be possible, but it's likely to require serious effort and still may not succeed. As I said, Chris Murphy or someone else with experience at trying to recover raid56 should be along with more detail, if you'd still prefer to go to that extra effort regardless of the real chance it won't help, in case it can. -- Duncan - List replies preferred. No HTML msgs. "Every nonfree program has a lord, a master -- and if you use the program, he is your master." Richard Stallman -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
