@Override
    public String toString() {
      return Path.SEPARATOR + backupRoot + Path.SEPARATOR + backupId + Path.SEPARATOR + walFile;
    }
This class provides API to access backup system table<br>
Backup system table schema:<br>
<p>
<ul>
<li>1. Backup sessions rowkey= "session:"+backupId; value =serialized BackupInfo</li>
<li>2. Backup start code rowkey = "startcode:"+backupRoot; value = startcode</li>
<li>3. Incremental backup set rowkey="incrbackupset:"+backupRoot; table="meta:"+tablename of
include table; value=empty</li>
<li>4. Table-RS-timestamp map rowkey="trslm:"+backupRoot+table_name; value = map[RS-> last WAL
timestamp]</li>
<li>5. RS - WAL ts map rowkey="rslogts:"+backupRoot +server; value = last WAL timestamp</li>
<li>6. WALs recorded rowkey="wals:"+WAL unique file name; value = backupId and full WAL file
name</li>
</ul>
</p>
hbase-backup/src/main/java/org/apache/hadoop/hbase/backup/impl/BackupSystemTable.java