On Sun, Dec 20, 2015 at 7:23 PM, Qu Wenruo <quwen...@cn.fujitsu.com> wrote: > > > Chris Murphy wrote on 2015/12/20 19:12 -0700: >> >> On Sun, Dec 20, 2015 at 6:43 PM, Qu Wenruo <quwen...@cn.fujitsu.com> >> wrote: >>> >>> >>> >>> Chris Murphy wrote on 2015/12/20 15:31 -0700: >> >> >>>> I think the cause is related to bus power with buggy USB 3 LPM >>>> firmware (these enclosures are cheap maybe $6). I've found some >>>> threads about this being a problem, but it's not expected to cause any >>>> corruptions. So, the fact Btrfs picks up one some problems might prove >>>> that (somewhat) incorrect. >>> >>> >>> >>> Seems possible. Maybe some metadata just failed to reach disk. >>> BTW, did I asked for a btrfs-show-super output? >> >> >> Nope. I will attach to this email below for both devices. >> >>> If that's the case, superblock on device 2 maybe older than superblock on >>> device 1. >> >> >> Yes, looks iike devid 1 transid 4924, and devid 2 transid 4923. And >> it's devid 2 that had device reset and write errors when it vanished >> and reappeared as a different block device. >> > > Now all the problem is explained. > > You should be good to mount it rw, as RAID1 will handle all the problem. > Then you can either use scrub on dev2 to fix all the generation mismatch. > > Although I prefer to wipe dev2 and mount dev1 as degraded, and replace the > missing dev2 with a good device/usb port.
Yeah. Best info I have right now is this particular make/model of USB 3.0 enclosure is common and sometimes has this reset and vanish problem with only certain controllers. In my case all four of the same kind of enclosure does this but only with 900mA ports. There's never a problem with 1.5A ports. I think it's just a slightly out of spec product. But usb-storage kernel developers said the warnings shouldn't result in corruptions. Another user with the same enclosure reported the problem only happens on Linux, not Windows, on the same host hardware. So it could also be some Linux SCSI layer error handling that's not working around a pre-existing issue when the device is flaky. Thanks! -- 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
