On Thu, Sep 15, 2016 at 1:44 AM, Alexandre Poux <pums...@gmail.com> wrote: > I had a btrfs partition on a 6 disk array without raid (metadata in > raid10, but data in single), and one of the disks just died. > > So I lost some of my data, ok, I knew that. > > But two question : > > * > > Is it possible to know (using metadata I suppose) what data I have > lost ?
The safest option is to remount read only and do a read only scrub. That will spit out messages for corrupt (missing) metadata and data, to the kernel message buffer. The missing data will appear as corrupt files that can't be fixed with full file paths. There will likely be so many that dmesg will be useless so you'll need to use journalctl -fk to follow the scrub; or journalctl -bk after the fact or even -b-1 -k or -b-2 -k, etc.; or /var/log/messages as it's probably going to exceed the kernel message buffer, so dmesg won't help. > Is it possible to do some king of a "btrfs delete missing" on this > kind of setup, in order to recover access in rw to my other data, or > I must copy all my data on a new partition That *should* work :) Except that your file system with 6 drives is too full to be shrunk to 5 drives. Btrfs will either refuse, or get confused, about how to shrink a nearly full 6 drive volume into 5. So you'll have to do one of three things: 1. Add a 2+TB drive, then remove the missing one; OR 2. btrfs replace is faster and is raid10 reliable; OR 3. Read only scrub to get a file listing of bad files, then remount read-write degraded and delete them all. Now you maybe can do a device delete missing. But it's still a tight fit, it basically has to balance things out to get it to fit on an odd number of drives, it may actually not work even though there seems to be enough total space, there has to be enough space on FOUR drives. I'd go with option 2. And that should still spit out the paths to bad files. If the replace works, I'm pretty sure you still need to delete all of the files that are missing in order to get rid of the corruption warnings on any subsequent scrub or balance. > > btrfs --version : > btrfs-progs v4.7.1 You should upgrade to 4.7.2 or downgrade to 4.6.1 before doing btrfs check. Not urgent so long as you don't actually do a repair with this version. -- 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
