Hadoop+HBase平台上安装snappy
在测试Apache Phoenix过程中，遇到了许多问题，首当其冲的就是缺少snappy压缩包。没办法，hbase-0.98.6.1没有自带，就只能自己安装了。首先当然还是上网搜一搜，看有没有写的比较好的安装步骤。结果发现，千篇一律，都是要下载编译一个貌似是hadoop-snappy的包。仔细看了看过程，还挺吓人的，中间出现了各种错误，甚至还对gcc的版本有要求。一气之下，就不想装了（其实是比较懒了嘿嘿）。
然后某一天突然看到了这篇博客：How to install snappy with HBase 0.94.x，作者说他摸索了3天才找出来这个不走弯路的办法，且仅需5分钟就能搞定(方法很简单，但我还是花了大概5个小时的时间，在Ubuntu上安装东西，你懂的。。。)
文章中介绍了一种安装在HBase上安装snappy的方法，很简单，于是决定一试，现将这篇文中讲到的方法翻译过来与大家分享：
1、检查snappy压缩包是否安装
命令为：bin/hbase org.apache.hadoop.hbase.util.CompressionTest file:///tmp/test.txt snappy
如果显示信息为：
12/12/03 10:30:02 WARN metrics.SchemaConfigured: Could not determine table and column family of the HFile path file:/tmp/test.txt. Expecting at least 5 path components.
12/12/03 10:30:02 WARN snappy.LoadSnappy: Snappy native library not loaded
Exception in thread "main" java.lang.RuntimeException: native snappy library not available
at org.apache.hadoop.io.compress.SnappyCodec.getCompressorType(SnappyCodec.java:123)
at org.apache.hadoop.io.compress.CodecPool.getCompressor(CodecPool.java:100)
at org.apache.hadoop.io.compress.CodecPool.getCompressor(CodecPool.java:112)
at org.apache.hadoop.hbase.io.hfile.Compression$Algorithm.getCompressor(Compression.java:264)
at org.apache.hadoop.hbase.io.hfile.HFileBlock$Writer.<init>(HFileBlock.java:739)
at org.apache.hadoop.hbase.io.hfile.HFileWriterV2.finishInit(HFileWriterV2.java:127)
at org.apache.hadoop.hbase.io.hfile.HFileWriterV2.<init>(HFileWriterV2.java:118)
at org.apache.hadoop.hbase.io.hfile.HFileWriterV2$WriterFactoryV2.createWriter(HFileWriterV2.java:101)
at org.apache.hadoop.hbase.io.hfile.HFile$WriterFactory.create(HFile.java:394)
at org.apache.hadoop.hbase.util.CompressionTest.doSmokeTest(CompressionTest.java:108)
则说明snappy压缩包没有安装；
2、下载snappy-*.tar.gz压缩包(只要和hbase版本兼容就可以，我的是snappy-1.1.1.tar.gz)，解压；
3、进入snappy目录，进行编译，两条命令：
./configure
make
4、make完之后会产生一个libsnappy.so文件(这就是我们所需要的库！！！)，正常情况下出现在当前目录./libs/libsnappy.so，但是很多时候不按套路出牌，跑到别的文件夹下了，如果make没有出错，可以在根目录search一下，肯定能找到这个文件；
5、将生成的这个libsnappy.so拷贝到HBase的lib/native/Linux-ARCH目录下，ARCH代表 amd64 或 i386-32，注意，对于amd64的HBase可能没有这个目录，此时，需要手动创建：
mkdir /opt/hbase-0.98.6.1/lib/native/Linux-amd64-64
6、如果还是不确定HBase在哪里查找lib，那么可以修改log4j文件中的日志级别(log level)进行调试；
7、重新运行第1步中的命令，现在看到的信息应该为：
12/12/03 10:34:35 INFO util.ChecksumType: Checksum can use java.util.zip.CRC32
12/12/03 10:34:35 INFO util.ChecksumType: org.apache.hadoop.util.PureJavaCrc32C not available.
12/12/03 10:34:35 DEBUG util.FSUtils: Creating file:file:/tmp/test.txtwith permission:rwxrwxrwx
12/12/03 10:34:35 WARN util.NativeCodeLoader: Unable to load native-hadoop library for your platform... using builtin-java classes where applicable
12/12/03 10:34:35 WARN metrics.SchemaConfigured: Could not determine table and column family of the HFile path file:/tmp/test.txt. Expecting at least 5 path components.
12/12/03 10:34:35 WARN snappy.LoadSnappy: Snappy native library is available
12/12/03 10:34:35 WARN snappy.LoadSnappy: Snappy native library not loaded
Exception in thread "main" java.lang.RuntimeException: native snappy library not available
at org.apache.hadoop.io.compress.SnappyCodec.getCompressorType(SnappyCodec.java:123)
at org.apache.hadoop.io.compress.CodecPool.getCompressor(CodecPool.java:100)
at org.apache.hadoop.io.compress.CodecPool.getCompressor(CodecPool.java:112)
at org.apache.hadoop.hbase.io.hfile.Compression$Algorithm.getCompressor(Compression.java:264)
at org.apache.hadoop.hbase.io.hfile.HFileBlock$Writer.<init>(HFileBlock.java:739)
at org.apache.hadoop.hbase.io.hfile.HFileWriterV2.finishInit(HFileWriterV2.java:127)
at org.apache.hadoop.hbase.io.hfile.HFileWriterV2.<init>(HFileWriterV2.java:118)
at org.apache.hadoop.hbase.io.hfile.HFileWriterV2$WriterFactoryV2.createWriter(HFileWriterV2.java:101)
at org.apache.hadoop.hbase.io.hfile.HFile$WriterFactory.create(HFile.java:394)
at org.apache.hadoop.hbase.util.CompressionTest.doSmokeTest(CompressionTest.java:108)
at org.apache.hadoop.hbase.util.CompressionTest.main(CompressionTest.java:138)
8、可以看到，snappy已经可以找到了，但是还没有加载(not loaded)。想加载的话，还需要拷贝hadoop的本地库到与libsnappy.so同一个路径下，hadoop的本地库路径为：
hadoop-1.2.1/lib/native/Linux-ARCH/libhadoop.so；
如果这个路径下没有，可以根据所使用的hadoop版本到 https://archive.apache.org/dist/hadoop/core/ 下载相应的tar.gz包，解压之后就能找到所需要的文件了；
9、再次运行测试命令(第1步中的命令)，可以得到：
12/12/03 10:37:48 INFO util.ChecksumType: org.apache.hadoop.util.PureJavaCrc32 not available.
12/12/03 10:37:48 INFO util.ChecksumType: Checksum can use java.util.zip.CRC32
12/12/03 10:37:48 INFO util.ChecksumType: org.apache.hadoop.util.PureJavaCrc32C not available.
12/12/03 10:37:48 DEBUG util.FSUtils: Creating file:file:/tmp/test.txtwith permission:rwxrwxrwx
12/12/03 10:37:48 INFO util.NativeCodeLoader: Loaded the native-hadoop library
12/12/03 10:37:48 WARN metrics.SchemaConfigured: Could not determine table and column family of the HFile path file:/tmp/test.txt. Expecting at least 5 path components.
12/12/03 10:37:48 WARN snappy.LoadSnappy: Snappy native library is available
12/12/03 10:37:48 INFO snappy.LoadSnappy: Snappy native library loaded
12/12/03 10:37:48 INFO compress.CodecPool: Got brand-new compressor
12/12/03 10:37:48 DEBUG hfile.HFileWriterV2: Initialized with CacheConfig:disabled
12/12/03 10:37:49 WARN metrics.SchemaConfigured: Could not determine table and column family of the HFile path file:/tmp/test.txt. Expecting at least 5 path components.
12/12/03 10:37:49 INFO compress.CodecPool: Got brand-new decompressor
SUCCESS
看到SUCCESS，说明安装成功，snappy压缩包可以使用，搞定。
ps：建议大家可以去看下这篇文章
网址：http://www.spaggiari.org/index.php/hbase/how-to-install-snappy-with#.VREJ__Sl8tM
注意：如果在make过程中出错，在重新make时一定要把之前的snappy文件夹删除，重新解压出一个新的文件夹，切记