Looking at the diags this might be an xfs issue/bug:
Aug 13 15:07:16 Tower kernel: XFS (md3): Internal error !uuid_equal(&mp->m_sb.sb_uuid, &head->h_fs_uuid) at line 278 of file fs/xfs/xfs_log_recover.c. Caller xlog_header_check_mount+0x4d/0x96 [xfs]
You can try installing latest xfs_progs (5.7.0), it might help, download from here then put the txz file on a folder called "extra" on your flash drive, reboot, after boot check that it loaded (xfs_repair -V) and run it again on disk3.
Whether it helps or not don't forget to then remove the extra folder on the flash after it's done.