原本使用操作系統的快照進行備份還原，備份成功後，還原沒有成功（參考：Backup and Restore with Filesystem Snapshots）
所以這個方法就先不記錄到這裡了。
當前測試以下？種備份還原方法（個人初學理解）：
1. 使用拷貝和替換數據庫文件進行備份還原
2. 使用mongodump和mongorestore
3. 使用mongoimport 和 mongoexport
1. 使用拷貝和替換數據庫文件進行備份還原（有些危險又不好）
1.1 備份
a. 在mongodb中執行db.fsyncLock()，刷新數據寫入磁盤並鎖住整個實例：
>db.fsyncLock()b. 打包壓縮整個數據庫目錄（也可以打包部分數據庫），作為備份：
[root@localhost ~]# tar -cvzf /root/mongodb_20150505.tar.gz /var/lib/mongoc. 在mongodb中執行db.fsyncUnlock()解鎖，備份步驟完成！~
>db.fsyncUnlock()
1.1 還原
a. 在mongodb中關閉服務（或者在操作系統層面關閉mongod服務）：
>use admin >db.shutdownServer()
b. 將mongo數據文件刪除！注意確認備份存在且正常！~否則回天無力！
[root@localhost ~]# rm -rf /var/lib/mongo/*c. 解壓備份的文件到根目錄下，相當於還原：
[root@localhost ~]# tar -xvzf /root/mongodb_20150505.tar.gz -C /d. 如果啟動不了服務，先刪除文件mongod.lock：
[root@localhost ~]# rm -f /var/lib/mongo/mongod.locke. 啟動服務，正常訪問。
[root@localhost ~]# service mongod start
a. 簡單備份還原本地數據庫的的方法，備份所有及還原所有：
mongodump mongorestore /root/dump
備份完成後在當前目錄將生成一個文件夾”dump“：
b. 還原單個數據庫時，指定要還原的數據庫及其備份目錄：
mongorestore --db test /root/dump/test還可以指定輸出路徑，使用計算機名：
mongodump --host localhost.localdomain --port 27017 --out /root/mongodump-2015-05-05 mongorestore --port 27017 --db test /root/mongodump-2015-05-05/test遠程備份時指定用戶名密碼（這個沒嘗試，參考官方例子）：
mongodump --host mongodb1.example.net --port 3017 --username user --password pass --out /opt/backup/mongodump-2013-10-24 mongorestore --host mongodb1.example.net --port 3017 --username user --password pass /opt/backup/mongodump-2013-10-24
# mongorestore --help
general options:
--help print usage
--version print the tool version and exit
verbosity options:
-v, --verbose more detailed log output (include multiple times for more verbosity, e.g. -vvvvv)
--quiet hide all log output
connection options:
-h, --host= mongodb host to connect to (setname/host1,host2 for replica sets)
--port= server port (can also use --host hostname:port)
ssl options:
--ssl connect to a mongod or mongos that has ssl enabled
--sslCAFile= the .pem file containing the root certificate chain from
the certificate authority
--sslPEMKeyFile= the .pem file containing the certificate and key
--sslPEMKeyPassword= the password to decrypt the sslPEMKeyFile, if necessary
--sslCRLFile= the .pem file containing the certificate revocation list
--sslAllowInvalidCertificates bypass the validation for server certificates
--sslAllowInvalidHostnames bypass the validation for server name
--sslFIPSMode use FIPS mode of the installed openssl library
authentication options:
-u, --username= username for authentication
-p, --password= password for authentication
--authenticationDatabase= database that holds the user's credentials
--authenticationMechanism= authentication mechanism to use
namespace options:
-d, --db= database to use
-c, --collection= collection to use
input options:
--objcheck validate all objects before inserting
--oplogReplay replay oplog for point-in-time restore
--oplogLimit= only include oplog entries before the provided Timestamp(seconds[:ordinal])
--restoreDbUsersAndRoles restore user and role definitions for the given database
--dir= input directory, use '-' for stdin
restore options:
--drop drop each collection before import
--writeConcern= write concern options e.g. --writeConcern majority,
--writeConcern '{w: 3, wtimeout: 500, fsync: true, j:true}' (defaults to 'majority')
--noIndexRestore don't restore indexes
--noOptionsRestore don't restore collection options
--keepIndexVersion don't update index version
--maintainInsertionOrder preserve order of documents during restoration
-j, --numParallelCollections= number of collections to restore in parallel (4 by default)
--numInsertionWorkersPerCollection= number of insert operations to run concurrently per collection (1 by default)
--stopOnError stop restoring if an error is encountered on insert (off bydefault)
3. 使用mongoimport 和 mongoexport
3.1 mongoexport導出
--type: 為json 或 csv
--fields: 選擇導出的列
#導出列{_id,id,size}為csv的格式
mongoexport --db test --collection tab --type=csv --fields _id,id,size --out /root/test_tab.csv
#導出json格式
mongoexport --db test --collection tab --type=json --out /root/test_tab.json
#輸出到shell中，查詢id=2 並按name升序輸出
mongoexport --db test --collection tab --query '{"id": 2}' --sort '{"name": 1}'
#查詢導出
mongoexport --db test --collection tab --type=csv --query '{"id": 2}' --fields _id,id --out /root/test_tab.csv
#簡寫選項[--db]和[--collection]，使用跳過和限制函數輸出
mongoexport -d test -c tab --sort '{"name": -1}' --limit 2 --skip 2 --out /root/test_tab.json
#若是遠程，需要添加參數：host，port，username，password
--host servername_or_ip --port 37017 --username user --password pass
查看幫助：mongoexport --help
general options:
--help print usage
--version print the tool version and exit
verbosity options:
-v, --verbose more detailed log output (include multiple times for more verbosity, e.g. -vvvvv)
--quiet hide all log output
connection options:
-h, --host= mongodb host to connect to (setname/host1,host2 for replica sets)
--port= server port (can also use --host hostname:port)
ssl options:
--ssl connect to a mongod or mongos that has ssl enabled
--sslCAFile= the .pem file containing the root certificate chain from the certificate authority
--sslPEMKeyFile= the .pem file containing the certificate and key
--sslPEMKeyPassword= the password to decrypt the sslPEMKeyFile, if necessary
--sslCRLFile= the .pem file containing the certificate revocation list
--sslAllowInvalidCertificates bypass the validation for server certificates
--sslAllowInvalidHostnames bypass the validation for server name
--sslFIPSMode use FIPS mode of the installed openssl library
authentication options:
-u, --username= username for authentication
-p, --password= password for authentication
--authenticationDatabase= database that holds the user's credentials
--authenticationMechanism= authentication mechanism to use
namespace options:
-d, --db= database to use
-c, --collection= collection to use
output options:
-f, --fields= comma separated list of field names (required for exporting CSV) e.g. -f "name,age"
--fieldFile= file with field names - 1 per line
--type= the output format, either json or csv (defaults to 'json')
-o, --out= output file; if not specified, stdout is used
--jsonArray output to a JSON array rather than one object per line
--pretty output JSON formatted to be human-readable
querying options:
-q, --query= query filter, as a JSON string, e.g., '{x:{$gt:1}}'
-k, --slaveOk allow secondary reads if available (default true)
--forceTableScan force a table scan (do not use $snapshot)
--skip= number of documents to skip
--limit= limit the number of documents to export
--sort= sort order, as a JSON string, e.g. '{x:1}'
#列"_id"也會導入，注意重復鍵 mongoimport --db mydb --collection tab --file /root/test_tab.json mongoimport --db mydb --collection tab --type csv --headerline --file /root/test_tab.csv #若是遠程，需要添加參數：host，port，username，password --host servername_or_ip --port 37017 --username user --password pass
general options:
--help print usage
--version print the tool version and exit
verbosity options:
-v, --verbose more detailed log output (include multiple times for more verbosity, e.g. -vvvvv)
--quiet hide all log output
connection options:
-h, --host= mongodb host to connect to (setname/host1,host2 for replica sets)
--port= server port (can also use --host hostname:port)
ssl options:
--ssl connect to a mongod or mongos that has ssl enabled
--sslCAFile= the .pem file containing the root certificate chain from the certificate authority
--sslPEMKeyFile= the .pem file containing the certificate and key
--sslPEMKeyPassword= the password to decrypt the sslPEMKeyFile, if necessary
--sslCRLFile= the .pem file containing the certificate revocation list
--sslAllowInvalidCertificates bypass the validation for server certificates
--sslAllowInvalidHostnames bypass the validation for server name
--sslFIPSMode use FIPS mode of the installed openssl library
authentication options:
-u, --username= username for authentication
-p, --password= password for authentication
--authenticationDatabase= database that holds the user's credentials
--authenticationMechanism= authentication mechanism to use
namespace options:
-d, --db= database to use
-c, --collection= collection to use
input options:
-f, --fields= comma separated list of field names, e.g. -f name,age
--fieldFile= file with field names - 1 per line
--file= file to import from; if not specified, stdin is used
--headerline use first line in input source as the field list (CSV and TSV
only)
--jsonArray treat input source as a JSON array
--type= input format to import: json, csv, or tsv (defaults to 'json')
ingest options:
--drop drop collection before inserting documents
--ignoreBlanks ignore fields with empty values in CSV and TSV
--maintainInsertionOrder insert documents in the order of their appearance in the input source
-j, --numInsertionWorkers= number of insert operations to run concurrently (defaults to 1)
--stopOnError stop importing at first insert/upsert error
--upsert insert or update objects that already exist
--upsertFields= comma-separated fields for the query part of the upsert
--writeConcern= write concern options e.g. --writeConcern majority,
--writeConcern '{w: 3, wtimeout: 500, fsync: true, j: true}'
(defaults to 'majority')
由於沒有做復制，復制中的備份到時再測試記錄吧！~
