On 2020/2/3 下午4:42, Skibbi wrote: > pon., 3 lut 2020 o 07:51 Qu Wenruo <quwenruo.btrfs@xxxxxxx> napisał(a): >> >>> I'm beginning to think that my Pi draws more power when used with >>> external drive (I used only pendrives so far) so I need to investigate >>> for power issues. >> >> That also looks promising. >> But since it's a USB hdd, what about try it with regular PC? > > I tried on widows and disk worked fine. I replaced Pi power supply and > surprise-surprise my disk is working fine! Btrfs + luks encryption. So > it seems power was the culprit. That's great to know! > However I'm a bit concerned about stability of the filesystem. I would > expect some data loss when drive is disconnected, but why the whole > filesystem is broken? It depends on the timing. In fact, as your initial report said, btrfs even succeeded to read some tree copy from the disk when we lost the device for a while. And finally goes RO if btrfs fails to write any tree blocks. In all cases, btrfs shouldn't fail if all disks follows FUA/FLUSH behavior (aka, if FUA/FLUSH returns, all related write should reach disk). > I can't ensure that power failures will not happen in the future, so > I'm still not sure if I should go with btrfs? > IIRC, either other fses just ignore any write error (and cause more serious problem later, not only data corruption but also metadata corruption) or just fail like btrfs when disks suddenly disappear. If the disk is not reliable, then it depends on what really you want. A kinda paranoid fs which refuses to further screw up the fs, or a fs ignoring most errors until the whole thing experience a rapid unscheduled disassembly. Thanks, Qu
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