/data1 went into read-only today, which means file system faulty.  It might be caused by a temporary power loss of the RAID device in the strong storm on Monday.  It has been temporarily taken offline for fsck.
Will be back online some time tomorrow.  Some data loss is expected.

After salvaged the data off /data1, the error on the volume has been pinned out.  The damage was limited to root directory and a few other directories.  I have rebuilt them and it passed fsck.  Minimum errors found and nothing dropped into /lost+found.  Rsync trial run over back up shows no files that are in backup are missing or damaged.  

This sounds to me a happy ending.  Please check your data  consistency to ensure minimum loss.