private void initializeWarmup(final CancelableProgressable reporter) throws IOException {
    MonitoredTask status = TaskMonitor.get().createStatus("Initializing region " + this);
    // Initialize all the HStores
    status.setStatus("Warmup all stores of " + this.getRegionInfo().getRegionNameAsString());
    try {
      initializeStores(reporter, status, true);
    } finally {
      status.markComplete("Warmed up " + this.getRegionInfo().getRegionNameAsString());
    }
  }
Open all Stores.
@return Highest sequenceId found out in a Store.
hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/HRegion.java