Mongodb自带了mongodump和mongorestore这两个工具来实现对数据的备份和恢复。
mongodump能够在Mongodb运行时进行备份，它的工作原理是对运行的Mongodb做查询，然后将所有查到的文档写入磁盘。但是存在的问题时使用mongodump产生的备份不一定是数据库的实时快照，如果我们在备份时对数据库进行了写入操作，则备份出来的文件可能不完全和Mongodb实时数据相等。另外在备份时可能会对其它客户端性能产生不利的影响。
mongodump用法如下：
[root@localhost mongodb]# ./bin/mongodump --help
Export MongoDB data to BSON files.
options:
--help produce help message
-v [ --verbose ] be more verbose (include multiple times for more
verbosity e.g. -vvvvv)
--version print the program's version and exit
-h [ --host ] arg mongo host to connect to ( <set name>/s1,s2 for
sets)
--port arg server port. Can also use --host hostname:port
--ipv6 enable IPv6 support (disabled by default)
-u [ --username ] arg username
-p [ --password ] arg password
--dbpath arg directly access mongod database files in the given
path, instead of connecting to a mongod server -
needs to lock the data directory, so cannot be used
if a mongod is currently accessing the same path
--directoryperdb if dbpath specified, each db is in a separate
directory
--journal enable journaling
-d [ --db ] arg database to use
-c [ --collection ] arg collection to use (some commands)
-o [ --out ] arg (=dump) output directory or "-" for stdout
-q [ --query ] arg json query
--oplog Use oplog for point-in-time snapshotting
--repair try to recover a crashed database
--forceTableScan force a table scan (do not use $snapshot)参数说明：
-h:指明数据库宿主机的IP
-u:指明数据库的用户名
-p:指明数据库的密码
-d:指明数据库的名字
-c:指明collection的名字
-o:指明到要导出的文件名
-q:指明导出数据的过滤条件
具体使用示例如下：
[root@localhost mongodb]# ./bin/mongodump -d test -o data/backup connected to: 127.0.0.1 DATABASE: test to data/backup/test test.system.indexes to data/backup/test/system.indexes.bson 9 objects test.users to data/backup/test/users.bson 3 objects test.games to data/backup/test/games.bson 1 objects test.blog.post to data/backup/test/blog.post.bson 1 objects test.lists to data/backup/test/lists.bson 1 objects test.math to data/backup/test/math.bson 1 objects test.map to data/backup/test/map.bson 8 objects test.my_collection to data/backup/test/my_collection.bson 0 objects test.foo to data/backup/test/foo.bson 6 objects test.system.users to data/backup/test/system.users.bson 1 objectsmongorestore是Mongodb从备份中恢复数据的工具，它主要用来获取mongodump的输出结果，并将备份的数据插入到运行的Mongodb中。
mongorestore命令使用方法如下：
[root@localhost mongodb]# ./bin/mongorestore --help
usage: ./bin/mongorestore [options] [directory or filename to restore from]
options:
--help produce help message
-v [ --verbose ] be more verbose (include multiple times for more
verbosity e.g. -vvvvv)
--version print the program's version and exit
-h [ --host ] arg mongo host to connect to ( <set name>/s1,s2 for sets)
--port arg server port. Can also use --host hostname:port
--ipv6 enable IPv6 support (disabled by default)
-u [ --username ] arg username
-p [ --password ] arg password
--dbpath arg directly access mongod database files in the given
path, instead of connecting to a mongod server -
needs to lock the data directory, so cannot be used
if a mongod is currently accessing the same path
--directoryperdb if dbpath specified, each db is in a separate
directory
--journal enable journaling
-d [ --db ] arg database to use
-c [ --collection ] arg collection to use (some commands)
--objcheck validate object before inserting
--filter arg filter to apply before inserting
--drop drop each collection before import
--oplogReplay replay oplog for point-in-time restore
--keepIndexVersion don't upgrade indexes to newest version参数说明：
-h:指明数据库宿主机的IP
-u:指明数据库的用户名
-p:指明数据库的密码
-d:指明数据库的名字
-c:指明collection的名字
-o:指明到要备份的文件名
-q:指明备份数据的过滤条件
具体使用示例如下：
[root@localhost mongodb]# ./bin/mongorestore -d test --drop data/backup/test/
connected to: 127.0.0.1
Tue Aug 14 01:18:17 data/backup/test/games.bson
Tue Aug 14 01:18:17 going into namespace [test.games]
Tue Aug 14 01:18:17 dropping
1 objects found
Tue Aug 14 01:18:17 data/backup/test/foo.bson
Tue Aug 14 01:18:17 going into namespace [test.foo]
Tue Aug 14 01:18:17 dropping
6 objects found
Tue Aug 14 01:18:17 data/backup/test/blog.post.bson
Tue Aug 14 01:18:17 going into namespace [test.blog.post]
Tue Aug 14 01:18:17 dropping
1 objects found
Tue Aug 14 01:18:17 data/backup/test/lists.bson
Tue Aug 14 01:18:17 going into namespace [test.lists]
Tue Aug 14 01:18:17 dropping
1 objects found
Tue Aug 14 01:18:17 data/backup/test/map.bson
Tue Aug 14 01:18:17 going into namespace [test.map]
Tue Aug 14 01:18:17 dropping
8 objects found
Tue Aug 14 01:18:17 data/backup/test/math.bson
Tue Aug 14 01:18:17 going into namespace [test.math]
Tue Aug 14 01:18:17 dropping
1 objects found
Tue Aug 14 01:18:17 data/backup/test/system.users.bson
Tue Aug 14 01:18:17 going into namespace [test.system.users]
1 objects found
Tue Aug 14 01:18:17 data/backup/test/my_collection.bson
Tue Aug 14 01:18:17 going into namespace [test.my_collection]
Tue Aug 14 01:18:17 dropping
Tue Aug 14 01:18:17 file data/backup/test/my_collection.bson empty, skipping
Tue Aug 14 01:18:17 data/backup/test/users.bson
Tue Aug 14 01:18:17 going into namespace [test.users]
Tue Aug 14 01:18:17 dropping
3 objects found
Tue Aug 14 01:18:17 data/backup/test/system.indexes.bson
Tue Aug 14 01:18:17 going into namespace [test.system.indexes]
Tue Aug 14 01:18:17 dropping
Tue Aug 14 01:18:17 { key: { _id: 1 }, ns: "test.users", name: "_id_" }
Tue Aug 14 01:18:17 { key: { _id: 1 }, ns: "test.games", name: "_id_" }
Tue Aug 14 01:18:17 { key: { _id: 1 }, ns: "test.blog.post", name: "_id_" }
Tue Aug 14 01:18:17 { key: { _id: 1 }, ns: "test.lists", name: "_id_" }
Tue Aug 14 01:18:17 { key: { _id: 1 }, ns: "test.math", name: "_id_" }
Tue Aug 14 01:18:17 { key: { _id: 1 }, ns: "test.map", name: "_id_" }
Tue Aug 14 01:18:17 { key: { gps: "2d" }, ns: "test.map", name: "gps_", min: -180.0, max: 181.0 }
Tue Aug 14 01:18:17 { key: { _id: 1 }, ns: "test.foo", name: "_id_" }
Tue Aug 14 01:18:17 { key: { _id: 1 }, ns: "test.system.users", name: "_id_" }
9 objects found
备注：还原指定数据库，数据文件需要指定到备份文件下面的子目录，如果不指定子目录，会报以下错误。
[root@localhost Desktop]# mongorestore -u rex -p 123456 -d test /var/lib/mongo/mongobak/
connected to: 127.0.0.1
ERROR: root directory must be a dump of a single database
when specifying a db name with --db
use the --help option for more information
正确做法：[root@localhost Desktop]# mongorestore -u rex -p 123456 -d test /var/lib/mongo/mongobak/test/
另：使用--drop可在恢复前删除集合(若存在),否则数据就会与现有集合数据合并,可能会覆盖一些文档.
[root@localhost Desktop]# mongorestore -u rex -p 123456 -d test --drop /var/lib/mongo/mongobak/test/
参考文章：
http://chenzhou123520.iteye.com/blog/1630993