On 2020/2/7 下午2:16, Chiung-Ming Huang wrote:
> Qu Wenruo <quwenruo.btrfs@gmx.com> 於 2020年2月7日 週五 下午12:00寫道：
>>
>> All these subvolumes had a missing root dir. That's not good either.
>> I guess btrfs-restore is your last chance, or RO mount with my
>> rescue=skipbg patchset:
>> https://patchwork.kernel.org/project/linux-btrfs/list/?series=170715
>>
> 
> Is it possible to use original disks to keep the restored data safely?
> I would like
> to restore the data of /dev/bcache3 to the new btrfs RAID0 at the first and then
> add it to the new btrfs RAID0. Does `btrfs restore` need metadata or something
> in /dev/bcache3 to restore /dev/bcache2 and /dev/bcache4?

Devid 1 (bcache 2) seems OK to be missing, as all its data and metadata
are in RAID1.

But it's strongly recommended to test without wiping bcache2, to make
sure btrfs-restore can salvage enough data, then wipeing bcache2.

Thanks,
Qu

> 
> /dev/bcache2, ID: 1
>    Device size:             9.09TiB
>    Device slack:              0.00B
>    Data,RAID1:              3.93TiB
>    Metadata,RAID1:          2.00GiB
>    System,RAID1:           32.00MiB
>    Unallocated:             5.16TiB
> 
> /dev/bcache3, ID: 3
>    Device size:             2.73TiB
>    Device slack:              0.00B
>    Data,single:           378.00GiB
>    Data,RAID1:            355.00GiB
>    Metadata,single:         2.00GiB
>    Metadata,RAID1:         11.00GiB
>    Unallocated:             2.00TiB
> 
> /dev/bcache4, ID: 5
>    Device size:             9.09TiB
>    Device slack:              0.00B
>    Data,single:             2.93TiB
>    Data,RAID1:              4.15TiB
>    Metadata,single:         6.00GiB
>    Metadata,RAID1:         11.00GiB
>    System,RAID1:           32.00MiB
>    Unallocated:             2.00TiB
> 
> Regards,
> Chiung-Ming Huang
>