/**
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.hadoop.hdfs.server.namenode;
import java.io.IOException;
import org.apache.hadoop.raid.Codec;
/**
* This BlockPlacementPolicy uses a simple heuristic, random placement of
* the replicas of a newly-created block for all the files in the system,
* for the purpose of spreading out the
* group of blocks which used by RAID for recovering each other.
* This is important for the availability of the blocks.
*
* Replication of an existing block continues to use the default placement
* policy.
*
* This simple block placement policy does not guarantee that
* blocks on the RAID stripe are on different nodes. However, BlockMonitor
* will periodically scans the raided files and will fix the placement
* if it detects violation.
*/
public class BlockPlacementPolicyRaidRandom extends BlockPlacementPolicyRaid {
@Override
protected FileInfo getFileInfo(FSInodeInfo srcINode, String path) throws IOException {
FileInfo info = super.getFileInfo(srcINode, path);
if (info.type == FileType.NOT_RAID) {
return new FileInfo(FileType.SOURCE, Codec.getCodec("rs"));
}
return info;
}
}