Lost track of this...sorry. On Sun, Aug 28, 2016 at 12:04 PM, Hendrik Friedel <hend...@friedels.name> wrote: > Hi Chris, > > thanks for your reply -especially on a Sunday. >>> >>> I have a filesystem (three disks with no raid) >> >> >> So it's data single *and* metadata single? >> > No: > Data, single: total=8.14TiB, used=7.64TiB > System, RAID1: total=32.00MiB, used=912.00KiB > Metadata, RAID1: total=18.00GiB, used=16.45GiB > GlobalReserve, single: total=512.00MiB, used=0.00B >> >> >> >>> btrfs check will lead to "Couldn't open file system"
That's a bug worth filing. That bug report will need a URL for where you put the btrfs-image file. >> Maybe >> take advantage of the fact it does read only and recreate it. You >> could take a btrfs-image and btrfs-debug-tree first, > > And what do I do with it? Put it somewhere it can live a while, it might be months before a dev gets around to looking at it. I usually put them on google drive in the public folder, and then post the URL (get shareable link) in the bug report. > >> because there's >> some bug somewhere: somehow it became inconsistent, and can't be fixed >> at mount time or even with btrfs check. > > Ok, so is there any way to help you finding this bug? > Coming back to my objectives: > -Understand the reason behind the issue and prevent it in future > Finding the but would help on the above No idea. > > -If not possible to repair the filesystem: > -understand if the data that I read from the drive is valid or corrupted > Can you answer this? Other than nocow files which do not have csums, Btrfs will spit back an I/O error and path to the bad file rather than hand over data it thinks is corrupt (doesn't match csum). So data read from the volume should be valid. > > As mentioned: I do have a backup, a month old. The data does not change so > regularly, so most should be ok. > Now I have two sources of data: > the backup and the current degraded filesystem. > If data differs, which one do I take? Is it safe to use the more recent one > from the degraded filesystem? If data differs you have to figure out a way to inspect the file to determine which one is correct. Databases have their own consistency checks, for example, if it's an image, open it in a viewer - big problems will be visible, small problems might just be one wrong pixel and you may not even notice it. -- 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
