Cassandra的备份就是对现有的数据做一个快照,恢复则是把快照进行还原。不仅可以对全库做快照,也可以针对表、keyspace单独做备份。另外它也支持增量备份。
1、全量备份
[root@db03 ~]# nodetool snapshot
Requested creating snapshot(s) for [all keyspaces] with snapshot name [1570691336948] and options {skipFlush=false}
Snapshot directory: 1570691336948
操作完成后,可以通过listsnapshots验证,如下图所示:
备份完成后,系统会在每个表所在的目录下生成一个1570691336948文件夹,里面存放了每个表的备份数据。这里用rhnchecksum表进行说明,如下图所示:
2、增量备份
默认情况下,它的增量备份是禁用的,可以通过以下命令进行验证:
[root@db03 ~]# nodetool statusbackup
not running
启用增量备份,命令如下:
[root@db03 ~]# nodetool enablebackup
[root@db03 ~]# nodetool statusbackup
running
执行下备份如下:
[root@db03 spacewalk]# nodetool snapshot
Requested creating snapshot(s) for [all keyspaces] with snapshot name [1570695931097] and options {skipFlush=false}
Snapshot directory: 1570695931097
3、恢复数据
cassandra的恢复过程如下:
- 清空表
cqlsh:spacewalk> select count(*) from rhnchecksum;
count
---------
8404215
(1 rows)
Warnings :
Aggregation query used without partition key
cqlsh:spacewalk> truncate rhnchecksum;
cqlsh:spacewalk> select count(*) from rhnchecksum;
count
-------
0
(1 rows)
- 还原snapshot目录的数据
这里将snapshot目录的数据拷贝到数据目录,然后执行refresh,如下:[root@db03 rhnchecksum-dbbb8330dde111e99dfb45c418aaa2bc]# pwd /var/lib/cassandra/data/spacewalk/rhnchecksum-dbbb8330dde111e99dfb45c418aaa2bc [root@db03 rhnchecksum-dbbb8330dde111e99dfb45c418aaa2bc]# cp -ra snapshots/1570695931097/* . --如果有索引数据也要进行拷贝操作 [root@db03 rhnchecksum-dbbb8330dde111e99dfb45c418aaa2bc]# cp -ra snapshots/1570695931097/.rhnchecksum_idx/* .rhnchecksum_idx/
当把快照文件复制到对应表的目录下后,运行refresh命令加载新的SSTables 不需要重启机器节点。
[root@db03 ~]# nodetool refresh spacewalk rhnchecksum
--完成后,cassandra的日志会出现下面的提示:
[root@db03 ~]# tail -f /var/log/cassandra/system.log
INFO [RMI TCP Connection(68)-127.0.0.1] 2019-10-10 16:41:22,513 ColumnFamilyStore.java:734 - Loading new SSTables for spacewalk/rhnchecksum...
INFO [RMI TCP Connection(68)-127.0.0.1] 2019-10-10 16:41:22,517 ColumnFamilyStore.java:782 - Renaming new SSTable /var/lib/cassandra/data/spacewalk/rhnchecksum-dbbb8330dde111e99dfb45c418aaa2bc/md-47-big to /var/lib/cassandra/data/spacewalk/rhnchecksum-dbbb8330dde111e99dfb45c418aaa2bc/md-50-big
INFO [RMI TCP Connection(68)-127.0.0.1] 2019-10-10 16:41:22,548 ColumnFamilyStore.java:782 - Renaming new SSTable /var/lib/cassandra/data/spacewalk/rhnchecksum-dbbb8330dde111e99dfb45c418aaa2bc/md-49-big to /var/lib/cassandra/data/spacewalk/rhnchecksum-dbbb8330dde111e99dfb45c418aaa2bc/md-51-big
INFO [RMI TCP Connection(68)-127.0.0.1] 2019-10-10 16:41:22,567 ColumnFamilyStore.java:782 - Renaming new SSTable /var/lib/cassandra/data/spacewalk/rhnchecksum-dbbb8330dde111e99dfb45c418aaa2bc/md-48-big to /var/lib/cassandra/data/spacewalk/rhnchecksum-dbbb8330dde111e99dfb45c418aaa2bc/md-52-big
INFO [RMI TCP Connection(68)-127.0.0.1] 2019-10-10 16:41:22,589 ColumnFamilyStore.java:782 - Renaming new SSTable /var/lib/cassandra/data/spacewalk/rhnchecksum-dbbb8330dde111e99dfb45c418aaa2bc/md-46-big to /var/lib/cassandra/data/spacewalk/rhnchecksum-dbbb8330dde111e99dfb45c418aaa2bc/md-53-big
INFO [RMI TCP Connection(68)-127.0.0.1] 2019-10-10 16:41:22,610 ColumnFamilyStore.java:817 - Loading new SSTables and building secondary indexes for spacewalk/rhnchecksum: [BigTableReader(path='/var/lib/cassandra/data/spacewalk/rhnchecksum-dbbb8330dde111e99dfb45c418aaa2bc/md-52-big-Data.db'), BigTableReader(path='/var/lib/cassandra/data/spacewalk/rhnchecksum-dbbb8330dde111e99dfb45c418aaa2bc/md-51-big-Data.db'), BigTableReader(path='/var/lib/cassandra/data/spacewalk/rhnchecksum-dbbb8330dde111e99dfb45c418aaa2bc/md-53-big-Data.db'), BigTableReader(path='/var/lib/cassandra/data/spacewalk/rhnchecksum-dbbb8330dde111e99dfb45c418aaa2bc/md-50-big-Data.db')]
INFO [RMI TCP Connection(68)-127.0.0.1] 2019-10-10 16:41:22,614 SecondaryIndexManager.java:366 - Submitting index build of rhnchecksum_idx for data in BigTableReader(path='/var/lib/cassandra/data/spacewalk/rhnchecksum-dbbb8330dde111e99dfb45c418aaa2bc/md-52-big-Data.db'),BigTableReader(path='/var/lib/cassandra/data/spacewalk/rhnchecksum-dbbb8330dde111e99dfb45c418aaa2bc/md-51-big-Data.db'),BigTableReader(path='/var/lib/cassandra/data/spacewalk/rhnchecksum-dbbb8330dde111e99dfb45c418aaa2bc/md-53-big-Data.db'),BigTableReader(path='/var/lib/cassandra/data/spacewalk/rhnchecksum-dbbb8330dde111e99dfb45c418aaa2bc/md-50-big-Data.db')
INFO [Service Thread] 2019-10-10 16:41:34,134 GCInspector.java:284 - ConcurrentMarkSweep GC in 467ms. CMS Old Gen: 1227906720 -> 508200320; Code Cache: 35251328 -> 35276800; Metaspace: 45251080 -> 45251832; Par Eden Space: 6575264 -> 139631912; Par Survivor Space: 41943040 -> 14759936
INFO [Service Thread] 2019-10-10 16:41:43,679 GCInspector.java:284 - ParNew GC in 236ms. CMS Old Gen: 844136912 -> 967814552; Par Eden Space: 335544320 -> 0; Par Survivor Space: 35314704 -> 41943040
INFO [RMI TCP Connection(68)-127.0.0.1] 2019-10-10 16:47:00,987 SecondaryIndexManager.java:386 - Index build of rhnchecksum_idx complete
INFO [RMI TCP Connection(68)-127.0.0.1] 2019-10-10 16:47:00,987 ColumnFamilyStore.java:825 - Done loading load new SSTables for spacewalk/rhnchecksum
恢复完成后,验证数据如下图所示:
nodetool命令的选项中文解释参考:Cassandra nodetool常用操作