cassandra 之 快照(snapshots)與sstableloader 備份、恢復
阿新 • • 發佈：2018-11-15
一、cassandra的備份和恢復
cassandra的備份恢復主要是通過snapshots 來實現。
步驟：
備份階段：
1. 生成快照；
恢復階段：
1. 清空表的資料（truncate table tablename）或者建立表結構；
2. 把各個表複製到對應標的資料目錄下，覆蓋原來的資料；
3. refresh 載入恢復資料；
1、生成快照(snapshots)
語法：
nodetool -h 伺服器ip -p 埠號 snapshots 資料庫名 #全庫快照 nodetool -h 伺服器ip -p 埠號 snapshots -t 快照名稱 -kt 資料庫名.表名 #某個錶快照
注：不指定-t 會自動生成時間戳字串
生成好的snapshots 儲存在資料目錄對應的表目錄下的snapshots，例:table-uuid/snapshots/snapshotsname
[email protected]:~# nodetool -h localhost -p 7199 snapshot -t xn_dolphin_1-20181010 xn_dolphin_1
Requested creating snapshot(s) for [xn_dolphin_1] with snapshot name [xn_dolphin_1-20181010] and options {skipFlush=false}
Snapshot directory: xn_dolphin_1-20181010
2、刪除資料：
cqlsh:xn_dolphin_1> select count(*) from dolphin_conversation_result;
count
-------
53426
(1 rows)
Warnings :
Aggregation query used without partition key
cqlsh:xn_dolphin_1> truncate table dolphin_conversation_result;
#cassandra 在truncate table的時候會自動建立一個截斷表的快照，表目錄下的檔案除了backups snapshots兩個目錄，其他都會被刪除，刪除*.db 檔案
[email protected]:/var/lib/cassandra/data/xn_dolphin_1/dolphin_conversation_result-d9e929d0cc9511e8a7ad6d2c86545d91# nodetool listsnapshots
Snapshot Details:
Snapshot name Keyspace name Column family name True size Size on disk
truncated-1539182023411-dolphin_conversation_result xn_dolphin_1 dolphin_conversation_result 5.1 MiB 5.1 MiB
3、#複製快照檔案
[email protected]:/var/lib/cassandra/data/xn_dolphin_1/dolphin_conversation_result-d9e929d0cc9511e8a7ad6d2c86545d91# ls
backups snapshots
[email protected]:/var/lib/cassandra/data/xn_dolphin_1/dolphin_conversation_result-d9e929d0cc9511e8a7ad6d2c86545d91# cp snapshots/truncated-1539182023411-dolphin_conversation_result/* .
#許可權
[email protected]:/var/lib/cassandra/data/xn_dolphin_1/dolphin_conversation_result-d9e929d0cc9511e8a7ad6d2c86545d91# chown -R cassandra.cassandra *
4、#恢復資料
語法:nodetool -h 伺服器 -p 埠 refresh – 資料庫名 資料表名
注：port 為7199
#快照恢復是在schma存在的情況下恢復資料，因此確保schema存在
[email protected]:/var/lib/cassandra/data/xn_dolphin_1/dolphin_conversation_result-d9e929d0cc9511e8a7ad6d2c86545d91# cqlsh -k xn_dolphin_1
Connected to Test Cluster at 127.0.0.1:9042.
[cqlsh 5.0.1 | Cassandra 3.11.3 | CQL spec 3.4.4 | Native protocol v4]
Use HELP for help.
cqlsh:xn_dolphin_1> desc dolphin_conversation_result ;
CREATE TABLE xn_dolphin_1.dolphin_conversation_result (
siteid text,
converid text,
type int,
content text,
customerid text,
deal_content text,
deal_time bigint,
isdeal int,
submit_time bigint,
supplierid text,
PRIMARY KEY (siteid, converid, type)
) WITH CLUSTERING ORDER BY (converid ASC, type ASC)
AND bloom_filter_fp_chance = 0.01
AND caching = {'keys': 'ALL', 'rows_per_partition': 'NONE'}
AND comment = ''
AND compaction = {'class': 'org.apache.cassandra.db.compaction.SizeTieredCompactionStrategy', 'max_threshold': '32', 'min_threshold': '4'}
AND compression = {'chunk_length_in_kb': '64', 'class': 'org.apache.cassandra.io.compress.LZ4Compressor'}
AND crc_check_chance = 1.0
AND dclocal_read_repair_chance = 0.1
AND default_time_to_live = 0
AND gc_grace_seconds = 864000
AND max_index_interval = 2048
AND memtable_flush_period_in_ms = 0
AND min_index_interval = 128
AND read_repair_chance = 0.0
AND speculative_retry = '99PERCENTILE';
[email protected]:/var/lib/cassandra/data/xn_dolphin_1/dolphin_conversation_result-d9e929d0cc9511e8a7ad6d2c86545d91# ls
backups mc-1-big-CompressionInfo.db mc-1-big-Digest.crc32 mc-1-big-Index.db mc-1-big-Summary.db schema.cql
manifest.json mc-1-big-Data.db mc-1-big-Filter.db mc-1-big-Statistics.db mc-1-big-TOC.txt snapshots
[email protected]:/var/lib/cassandra/data/xn_dolphin_1/dolphin_conversation_result-d9e929d0cc9511e8a7ad6d2c86545d91# nodetool refresh -- xn_dolphin_1 dolphin_conversation_result
[email protected]:/var/lib/cassandra/data/xn_dolphin_1/dolphin_conversation_result-d9e929d0cc9511e8a7ad6d2c86545d91# cqlsh -k xn_dolphin_1
Connected to Test Cluster at 127.0.0.1:9042.
[cqlsh 5.0.1 | Cassandra 3.11.3 | CQL spec 3.4.4 | Native protocol v4]
Use HELP for help.
cqlsh:xn_dolphin_1> select count(*) from dolphin_conversation_result;
count
-------
53426
(1 rows)
Warnings :
Aggregation query used without partition key
二、sstableloader遷移工具
在cassandra的bin目錄下提供了一個sstableloader工具，這個工具專門用於把一個表的sstable檔案匯入到一個新的叢集中。
1.舊叢集環境：表是mykeyspace.mytable。你的資料存一個3個節點組成的叢集中，每個節點的資料都存在/opt/data目錄下。
2.新叢集環境：地址是192.168.31.185， 先在新叢集建離相同名字的keyspace和表結構。
3.在舊叢集環境裡執行：
bin/sstableloader -d 192.168.31.185 -u cassandra -pw cassandra -t 100 /opt/data/mykeyspace/mytable
其中-u是 使用者名稱 -pw是密碼 -t是限制流量100M/bps
等所有節點執行完畢，表資料就成功匯入到了新的叢集中，當然只要機器io和網路條件允許，你可以多個節點併發執行。
示例：
[email protected]:/$ sstableloader -d 192.168.31.185 -u cassandra -pw cassandra -t 100 /opt/bitnami/cassandra/data/data/xn_dolphin_1/dolphin_conversation_result-2c8866e0ce3711e89b4687b65adcf047/
WARN 16:25:38,358 Small commitlog volume detected at /opt/bitnami/cassandra/bin/../data/commitlog; setting commitlog_total_space_in_mb to 4348. You can override this in cassandra.yaml
WARN 16:25:38,377 Small cdc volume detected at /opt/bitnami/cassandra/bin/../data/cdc_raw; setting cdc_total_space_in_mb to 2174. You can override this in cassandra.yaml
WARN 16:25:38,669 Only 6.847GiB free across all data volumes. Consider adding more capacity to your cluster or removing obsolete snapshots
Established connection to initial hosts
Opening sstables and calculating sections to stream
Streaming relevant part of /bitnami/cassandra/data/data/xn_dolphin_1/dolphin_conversation_result-2c8866e0ce3711e89b4687b65adcf047/mc-1-big-Data.db to [/192.168.31.185]
progress: [/192.168.31.185]0:1/1 100% total: 100% 792.200KiB/s (avg: 792.200KiB/s)
progress: [/192.168.31.185]0:1/1 100% total: 100% 0.000KiB/s (avg: 634.013KiB/s)
Summary statistics:
Connections per host : 1
Total files transferred : 1
Total bytes transferred : 5.053MiB
Total duration : 8175 ms
Average transfer rate : 632.865KiB/s
Peak transfer rate : 792.200KiB/s
遷移完成！