老实说，虽然cassandra在业界不是很受待见，但是但从使用上来看，cassandra还是挺简单的，本次测试环境仍然是UBUNTU，集群中最简单的使用了2个节点。
首先安装java，这个可以参考我之前的博客：Ubuntu 11.04上安装jdk1.6+oracle 11g笔记 。一系列各种JAVA_HOME什么的配置完之后，应该可以看到这个
~$ java -version java version "1.8.0" Java(TM) SE Runtime Environment (build 1.8.0-b132) Java HotSpot(TM) 64-Bit Server VM (build 25.0-b70, mixed mode)
现在我用的版本是java 8。然后需要从cassandra官网上下载安装包，这个不再多说，我的版本是apache-cassandra-2.0.6-bin.tar.gz，ubuntu中好像没有cassandra的源。
然后是建立数据文件和log的目录并改变其所属用户和所属用户组，
XXXXX@XXXXX-asus:~$ sudo mkdir /var/lib/cassandra XXXXX@XXXXX-asus:~$ sudo chown XXXXX /var/lib/cassandra/ XXXXX@XXXXX-asus:~$ sudo chgrp XXXXX /var/lib/cassandra/ XXXXX@XXXXX-asus:~$ sudo mkdir /var/log/cassandra XXXXX@XXXXX-asus:~$ sudo chown XXXXX /var/log/cassandra/ XXXXX@XXXXX-asus:~$ sudo chgrp XXXXX /var/log/cassandra/ XXXXX@XXXXX-asus:~$ ll /var/lib/ | grep cas drwxr-xr-x 2 XXXXX XXXXX 4096 4月 13 11:09 cassandra/ XXXXX@XXXXX-asus:~$ ll /var/log/ | grep cas drwxr-xr-x 2 XXXXX XXXXX 4096 4月 13 11:09 cassandra/ XXXXX@XXXXX-asus:~$
当然，cassandra的数据和log文件是不是非要死板的放在/var/lib和/var/log下面呢？当然不是，有地方可以配置的，这里，为了便于实验，仍然采用默认配置。
解压cassandra的安装包后可以查看主要的配置文件，都在conf/目录下，conf/cassandra.yaml比较重要，其中需要着重注意的有以下一些配置项
cluster_name: 'TC01' num_tokens: 256 seed_provider: - class_name: org.apache.cassandra.locator.SimpleSeedProvider parameters: - seeds: "192.168.2.103" listen_address: 192.168.2.103 rpc_address: 192.168.2.103 endpoint_snitch: SimpleSnitch
cluster_name一定要修改，免得用默认的“Test Cluster”和他人冲突，所有有显示ip的地方都需要注意并修改，将127.0.0.1和localhost改为你的对外访问的ip，比如我的局域网ip就是192.168.2.103。
conf/cassandra.yaml中还有改动数据文件位置的选项，搜索/var/lib相关的选项修改即可，conf/log4j-server.properties中有改动log文件位置的选项，搜索/var/log相关的选项。这次实验中都没有修改这些选项。
然后启动cassandra，
XXXXX@XXXXX-asus:~/apache-cassandra-2.0.6$ cd bin/ XXXXX@XXXXX-asus:~/apache-cassandra-2.0.6/bin$ ./cassandra -f
用-f参数启动，可以看到cassandra启动超长的log，接着看一下状态
XXXXX@XXXXX-asus:~/apache-cassandra-2.0.6$ cd bin/ XXXXX@XXXXX-asus:~/apache-cassandra-2.0.6/bin$ ls cassandra cassandra-shuffle debug-cql.bat sstable2json sstableloader.bat sstablesplit.bat cassandra.bat cassandra-shuffle.bat json2sstable sstable2json.bat sstablemetadata.bat sstableupgrade cassandra-cli cqlsh json2sstable.bat sstablekeys sstablescrub sstableupgrade.bat cassandra-cli.bat cqlsh.bat nodetool sstablekeys.bat sstablescrub.bat stop-server cassandra.in.sh debug-cql nodetool.bat sstableloader sstablesplit XXXXX@XXXXX-asus:~/apache-cassandra-2.0.6/bin$ ./nodetool status Datacenter: datacenter1 ======================= Status=Up/Down |/ State=Normal/Leaving/Joining/Moving -- Address Load Tokens Owns (effective) Host ID Rack UN 192.168.2.103 40.92 KB 256 100.0% 80a96105-819a-40f2-ac7c-489285017de1 rack1
现在cassandra已经启动了节点1，节点2在一台虚拟机上（ip:192.168.2.102），其配置与节点1非常类似，要改动配置里面的seeds那一项的ip为节点1的ip
cluster_name: 'TC01' num_tokens: 256 seed_provider: - class_name: org.apache.cassandra.locator.SimpleSeedProvider parameters: - seeds: "192.168.2.103" listen_address: 192.168.2.102 rpc_address: 192.168.2.102 endpoint_snitch: SimpleSnitch
以同样的方式启动节点2，就可以在节点1中看到节点2已经加入到集群。此时，节点1的log中可以看到以下信息
WARN 17:36:15,477 Gossip stage has 1 pending tasks; skipping status check (no nodes will be marked down) INFO 17:36:16,358 Handshaking version with /192.168.2.102 INFO 17:36:17,999 Node /192.168.2.102 is now part of the cluster INFO 17:36:18,496 Handshaking version with /192.168.2.102 INFO 17:36:18,727 InetAddress /192.168.2.102 is now UP INFO 17:36:53,523 [Stream #24d92630-c2ef-11e3-9d13-81bcfc870408] Received streaming plan for Bootstrap INFO 17:36:54,336 [Stream #24d92630-c2ef-11e3-9d13-81bcfc870408] Session with /192.168.2.102 is complete INFO 17:36:54,586 [Stream #24d92630-c2ef-11e3-9d13-81bcfc870408] All sessions completed
如果用nodetool来看，可以看到以下信息
XXXXX@XXXXX-asus:~/apache-cassandra-2.0.6/bin$ ./nodetool status Datacenter: datacenter1 ======================= Status=Up/Down |/ State=Normal/Leaving/Joining/Moving -- Address Load Tokens Owns (effective) Host ID Rack UN 192.168.2.102 54.74 KB 256 100.0% 00782976-b020-43a7-8fa5-b7dee95e6f1e rack1 UN 192.168.2.103 45.75 KB 256 100.0% 80a96105-819a-40f2-ac7c-489285017de1 rack1
很清楚的可以看到2个节点全部在线。接下去开始实验集群的数据同步，先登陆node1节点，建立必要的keyspace和column family
XXXXX@XXXXX-asus:~/apache-cassandra-2.0.6/bin$ ./cassandra-cli -h 192.168.2.103 -p 9160 Connected to: "TC01" on 192.168.2.103/9160 Welcome to Cassandra CLI version 2.0.6 The CLI is deprecated and will be removed in Cassandra 3.0. Consider migrating to cqlsh. CQL is fully backwards compatible with Thrift data; see http://www.datastax.com/dev/blog/thrift-to-cql3 Type 'help;' or '?' for help. Type 'quit;' or 'exit;' to quit. [default@unknown] create keyspace test; fa857b42-d483-31a8-8ef0-b30251cf6f72 [default@unknown] use test; Authenticated to keyspace: test [default@test] create column family test_cf; 869e20c5-ab6f-349d-8466-a86454af18cc [default@test] show schema; WARNING: CQL3 tables are intentionally omitted from 'show schema' output. See https://issues.apache.org/jira/browse/CASSANDRA-4377 for details. create keyspace test with placement_strategy = 'NetworkTopologyStrategy' and strategy_options = {datacenter1 : 1} and durable_writes = true; use test; create column family test_cf with column_type = 'Standard' and comparator = 'BytesType' and default_validation_class = 'BytesType' and key_validation_class = 'BytesType' and read_repair_chance = 0.1 and dclocal_read_repair_chance = 0.0 and populate_io_cache_on_flush = false and gc_grace = 864000 and min_compaction_threshold = 4 and max_compaction_threshold = 32 and replicate_on_write = true and compaction_strategy = 'org.apache.cassandra.db.compaction.SizeTieredCompactionStrategy' and caching = 'KEYS_ONLY' and default_time_to_live = 0 and speculative_retry = 'NONE' and compression_options = {'sstable_compression' : 'org.apache.cassandra.io.compress.LZ4Compressor'} and index_interval = 128;
但是在插入数据的时候会发生奇怪的错误，用ascii函数可以解决
[default@test] set test_cf['num']['num1']=1111; org.apache.cassandra.serializers.MarshalException: cannot parse 'num1' as hex bytes [default@test] set test_cf[ascii('num')][ascii('num1')]=1111; Value inserted. Elapsed time: 97 msec(s).
原因是因为列族中使用了BytesType，如果用UTF8Type就不会有错了，drop之前的列族，重建
[default@test] create column family testcf with column_type = 'Standard' and comparator = 'UTF8Type' and default_validation_class = 'UTF8Type' and key_validation_class = 'UTF8Type'; 08656500-2f27-345f-bcf7-c58e225fb2ff [default@test] show schema; WARNING: CQL3 tables are intentionally omitted from 'show schema' output. See https://issues.apache.org/jira/browse/CASSANDRA-4377 for details. create keyspace test with placement_strategy = 'NetworkTopologyStrategy' and strategy_options = {datacenter1 : 1} and durable_writes = true; use test; create column family testcf with column_type = 'Standard' and comparator = 'UTF8Type' and default_validation_class = 'UTF8Type' and key_validation_class = 'UTF8Type' and read_repair_chance = 0.1 and dclocal_read_repair_chance = 0.0 and populate_io_cache_on_flush = false and gc_grace = 864000 and min_compaction_threshold = 4 and max_compaction_threshold = 32 and replicate_on_write = true and compaction_strategy = 'org.apache.cassandra.db.compaction.SizeTieredCompactionStrategy' and caching = 'KEYS_ONLY' and default_time_to_live = 0 and speculative_retry = 'NONE' and compression_options = {'sstable_compression' : 'org.apache.cassandra.io.compress.LZ4Compressor'} and index_interval = 128;
测试插入数据和查询，以及和node2之间的数据同步。先看node1上的插入数据
XXXXX@XXXXX-asus:~/apache-cassandra-2.0.6/bin$ ./cassandra-cli -h 192.168.2.103 -p 9160 Connected to: "TC01" on 192.168.2.103/9160 Welcome to Cassandra CLI version 2.0.6 The CLI is deprecated and will be removed in Cassandra 3.0. Consider migrating to cqlsh. CQL is fully backwards compatible with Thrift data; see http://www.datastax.com/dev/blog/thrift-to-cql3 Type 'help;' or '?' for help. Type 'quit;' or 'exit;' to quit. [default@unknown] use test; Authenticated to keyspace: test [default@test] set testcf['num']['num1']=1111; Value inserted. Elapsed time: 66 msec(s). [default@test] list testcf; Using default limit of 100 Using default cell limit of 100 ------------------- RowKey: num => (name=num1, value=1111, timestamp=1397389549047000) 1 Row Returned. Elapsed time: 823 msec(s). [default@test]
再看node2上的同步的结果
XXXXX@XXXXX-asus:~/apache-cassandra-2.0.6/bin$ ./cassandra-cli -h 192.168.2.102 -p 9160 Connected to: "TC01" on 192.168.2.102/9160 Welcome to Cassandra CLI version 2.0.6 The CLI is deprecated and will be removed in Cassandra 3.0. Consider migrating to cqlsh. CQL is fully backwards compatible with Thrift data; see http://www.datastax.com/dev/blog/thrift-to-cql3 Type 'help;' or '?' for help. Type 'quit;' or 'exit;' to quit. [default@unknown] use test; Authenticated to keyspace: test [default@test] list testcf; Using default limit of 100 Using default cell limit of 100 ------------------- RowKey: num => (name=num1, value=1111, timestamp=1397389549047000) 1 Row Returned. Elapsed time: 914 msec(s). [default@test]
可以看到数据已经同步到node2，时间戳一样。