设置多磁盘存储

clickhouse安装完成以后，配置了一个默认的存储空间， 这个只能配置一个目录，如果要使用多个磁盘目录，则需要配置磁盘组策略

查看当前的存储策略

select name, path, formatReadableSize(free_space) as free, formatReadableSize(total_space) as total, formatReadableSize(keep_free_space) as reserved from system.disks;

可以看到只有一个default

┌─name────┬─path─────────────────────┬─free─────┬─total────┬─reserved─┐
│ default │ /data06/clickhouse/ │ 1.54 TiB │ 1.82 TiB │ 0.00 B   │
└─────────┴──────────────────────────┴──────────┴──────────┴──────────┘

准备好磁盘目录

mkdir /data01/clickhouse
mkdir /data02/clickhouse
mkdir /data03/clickhouse
mkdir /data04/clickhouse
mkdir /data05/clickhousechown -R clickhouse:clickhouse /data01/clickhouse
chown -R clickhouse:clickhouse /data02/clickhouse
chown -R clickhouse:clickhouse /data03/clickhouse
chown -R clickhouse:clickhouse /data04/clickhouse
chown -R clickhouse:clickhouse /data05/clickhouse

添加配置

添加配置到/etc/clickhouse-server/config.xml 中

    <storage_configuration><disks><disk_hot1> <!-- 自定义磁盘名称 --><path>/data01/clickhouse/</path></disk_hot1> <disk_hot2><path>/data02/clickhouse/</path></disk_hot2><disk_hot3><path>/data03/clickhouse/</path></disk_hot3><disk_hot4><path>/data04/clickhouse/</path></disk_hot4><disk_hot5><path>/data05/clickhouse/</path></disk_hot5><disk_cold><path>/root/clickhouse_storage/cold/</path> <keep_free_space_bytes>1073741824</keep_free_space_bytes></disk_cold></disks><policies><jbod_police> <!-- 自定义策略名称 --><volumes><jbod> <!-- 自定义磁盘组名称 --><disk>disk_hot1</disk><disk>disk_hot2</disk><disk>disk_hot3</disk><disk>disk_hot4</disk><disk>disk_hot5</disk></jbod></volumes></jbod_police><hot_cold_police><volumes><hot><disk>disk_hot1</disk> <disk>disk_hot2</disk> <max_data_part_size_bytes>1048576</max_data_part_size_bytes></hot><cold><disk>disk_cold</disk></cold></volumes><move_factor>0.2</move_factor></hot_cold_police></policies></storage_configuration>

• keep_free_space_bytes：选填项，表示不被使用的磁盘空间大小
• jbod策略只需要配置一个磁盘组，part(如202107_0_0_0)储存轮询每个disk；适用于挂载了多块磁盘，但未配置RAID
• hot/cold策略配置hot和cold两个磁盘组, part未超过(max_data_part_size_bytes[选填项] * move_factor[选填项, 默认0.1])则储存在hot磁盘组，超过则储存在cold磁盘组；适用于挂载了SSD和HDD磁盘
• 磁盘策略可以配置多个

配置生效

依次重启每个节点：
/etc/init.d/clickhouse-server restart

再看磁盘disk就有多个了：

:) select name, path, formatReadableSize(free_space) as free, formatReadableSize(total_space) as total, formatReadableSize(keep_free_space) as reserved from system.disks;┌─name──────┬─path─────────────────────┬─free─────┬─total────┬─reserved─┐
│ default   │ /data03/clickhouse/ │ 1.54 TiB │ 1.82 TiB │ 0.00 B   │
│ disk_hot1 │ /data06/clickhouse/ │ 1.58 TiB │ 1.82 TiB │ 0.00 B   │
│ disk_hot2 │ /data07/clickhouse/ │ 1.61 TiB │ 1.82 TiB │ 0.00 B   │
│ disk_hot3 │ /data08/clickhouse/ │ 1.58 TiB │ 1.82 TiB │ 0.00 B   │
│ disk_hot4 │ /data09/clickhouse/ │ 1.58 TiB │ 1.82 TiB │ 0.00 B   │
│ disk_hot5 │ /data10/clickhouse/ │ 1.60 TiB │ 1.82 TiB │ 0.00 B   │
└───────────┴──────────────────────────┴──────────┴──────────┴──────────┘

存储策略也可以看到了，这个存储策略在建表的时候，可以指定

 :) select policy_name, volume_name, volume_priority, disks, formatReadableSize(max_data_part_size) max_data_part_size, move_factor from system.storage_policies;┌─policy_name─┬─volume_name─┬─volume_priority─┬─disks─────────────────────────────────────────────────────────┬─max_data_part_size─┬─move_factor─┐
│ default     │ default     │               1 │ ['default']                                                   │ 0.00 B             │           0 │
│ jbod_police │ jbod        │               1 │ ['disk_hot1','disk_hot2','disk_hot3','disk_hot4','disk_hot5'] │ 0.00 B             │         0.1 │
└─────────────┴─────────────┴─────────────────┴───────────────────────────────────────────────────────────────┴────────────────────┴─────────────┘