One thing I found out lately: dmesg gives me a unsupported option (100). I guess the btrfs created on my laptop is not compatible with the old 3.16, so it won't mount. In the end this might cause the errors being created on first reboot, when J1 tries to repair automatically?
mkfs.btrfs -d single -m single -n 4096 -L sailfish -O ^extref,^skinny-metadata -U <uuid>
> mkfs.btrfs -O list-all Filesystem features available: mixed-bg - mixed data and metadata block groups (0x4, compat=2.6.37, safe=2.6.37) extref - increased hardlink limit per file to 65536 (0x40, compat=3.7, safe=3.12, default=3.12) raid56 - raid56 extended format (0x80, compat=3.9) skinny-metadata - reduced-size metadata extent refs (0x100, compat=3.10, safe=3.18, default=3.18) no-holes - no explicit hole extents for files (0x200, compat=3.14, safe=4.0)
I do not have a publicly writable storage for file transfer. Will see, if I can get a ftp server running temporarily.