Storage 负载均衡¶

用户可以使用BALANCE语句平衡分片和 Raft leader 的分布，或者清空某些 Storage 服务器方便进行维护。详情请参见 BALANCE。

Danger

BALANCE命令通过创建和执行一组子任务来迁移数据和均衡分片分布，禁止停止集群中的任何机器或改变机器的 IP 地址，直到所有子任务完成，否则后续子任务会失败。

均衡分片分布¶

Enterpriseonly

仅企业版支持均衡分片分布。

Note

如果当前图空间已经有失败的均衡分片分布作业，无法开始新的均衡分片分布作业，只能恢复之前失败的作业。如果作业一直执行失败，可以先停止作业，再开始新的均衡分片分布作业。

BALANCE DATA语句会开始一个作业，将当前图空间的分片平均分配到所有 Storage 服务器。通过创建和执行一组子任务来迁移数据和均衡分片分布。

示例¶

以横向扩容 Nebula Graph 为例，集群中增加新的 Storage 主机后，新主机上没有分片。

执行命令SHOW HOSTS检查分片的分布。

nebual> SHOW HOSTS;
+-----------------+------+-----------+----------+--------------+-----------------------+------------------------+-------------+
| Host            | Port | HTTP port | Status   | Leader count | Leader distribution   | Partition distribution | Version     |
+-----------------+------+-----------+----------+--------------+-----------------------+------------------------+-------------+
| "192.168.8.101" | 9779 | 19669     | "ONLINE" | 0            | "No valid partition"  | "No valid partition"   | "3.1.0-ent" |
| "192.168.8.100" | 9779 | 19669     | "ONLINE" | 15           | "basketballplayer:15" | "basketballplayer:15"  | "3.1.0-ent" |
+-----------------+------+-----------+----------+--------------+-----------------------+------------------------+-------------+

进入图空间basketballplayer，然后执行命令BALANCE DATA将所有分片均衡分布。

nebula> USE basketballplayer;
nebula> BALANCE DATA;
+------------+
| New Job Id |
+------------+
| 2          |
+------------+

根据返回的任务ID，执行命令SHOW JOB <job_id>检查任务状态。

nebula> SHOW JOB 2;
+------------------------+------------------------------------------+-------------+---------------------------------+---------------------------------+-------------+
| Job Id(spaceId:partId) | Command(src->dst)                        | Status      | Start Time                      | Stop Time                       | Error Code  |
+------------------------+------------------------------------------+-------------+---------------------------------+---------------------------------+-------------+
| 2                      | "DATA_BALANCE"                           | "FINISHED"  | "2022-04-12T03:41:43.000000000" | "2022-04-12T03:41:53.000000000" | "SUCCEEDED" |
| "2, 1:1"               | "192.168.8.100:9779->192.168.8.101:9779" | "SUCCEEDED" | 2022-04-12T03:41:43.000000      | 2022-04-12T03:41:53.000000      | "SUCCEEDED" |
| "2, 1:2"               | "192.168.8.100:9779->192.168.8.101:9779" | "SUCCEEDED" | 2022-04-12T03:41:43.000000      | 2022-04-12T03:41:53.000000      | "SUCCEEDED" |
| "2, 1:3"               | "192.168.8.100:9779->192.168.8.101:9779" | "SUCCEEDED" | 2022-04-12T03:41:43.000000      | 2022-04-12T03:41:53.000000      | "SUCCEEDED" |
| "2, 1:4"               | "192.168.8.100:9779->192.168.8.101:9779" | "SUCCEEDED" | 2022-04-12T03:41:43.000000      | 2022-04-12T03:41:53.000000      | "SUCCEEDED" |
| "2, 1:5"               | "192.168.8.100:9779->192.168.8.101:9779" | "SUCCEEDED" | 2022-04-12T03:41:43.000000      | 2022-04-12T03:41:53.000000      | "SUCCEEDED" |
| "2, 1:6"               | "192.168.8.100:9779->192.168.8.101:9779" | "SUCCEEDED" | 2022-04-12T03:41:43.000000      | 2022-04-12T03:41:43.000000      | "SUCCEEDED" |
| "2, 1:7"               | "192.168.8.100:9779->192.168.8.101:9779" | "SUCCEEDED" | 2022-04-12T03:41:43.000000      | 2022-04-12T03:41:53.000000      | "SUCCEEDED" |
| "Total:7"              | "Succeeded:7"                            | "Failed:0"  | "In Progress:0"                 | "Invalid:0"                     | ""          |
+------------------------+------------------------------------------+-------------+---------------------------------+---------------------------------+-------------+

等待所有子任务完成，负载均衡进程结束，执行命令SHOW HOSTS确认分片已经均衡分布。

Note

BALANCE DATA不会均衡 leader 的分布。均衡 leader 请参见均衡 leader 分布。

nebula> SHOW HOSTS;
+-----------------+------+-----------+----------+--------------+----------------------+------------------------+-------------+
| Host            | Port | HTTP port | Status   | Leader count | Leader distribution  | Partition distribution | Version     |
+-----------------+------+-----------+----------+--------------+----------------------+------------------------+-------------+
| "192.168.8.101" | 9779 | 19669     | "ONLINE" | 7            | "basketballplayer:7" | "basketballplayer:7"   | "3.1.0-ent" |
| "192.168.8.100" | 9779 | 19669     | "ONLINE" | 8            | "basketballplayer:8" | "basketballplayer:8"   | "3.1.0-ent" |
+-----------------+------+-----------+----------+--------------+----------------------+------------------------+-------------+

如果有子任务失败，请执行RECOVER JOB <job_id>。如果重做负载均衡仍然不能解决问题，请到Nebula Graph社区寻求帮助。

停止负载均衡作业¶

停止负载均衡作业，请执行命令STOP JOB <job_id>。

如果没有正在执行的负载均衡作业，会返回错误。

如果有正在执行的负载均衡作业，会返回Job stopped。

Note

STOP JOB <job_id>不会停止正在执行的子任务，而是取消所有后续子任务，状态会置为INVALID，然后等待正在执行的子任执行完毕根据结果置为SUCCEEDED或FAILED。用户可以执行命令SHOW JOB <job_id>检查停止的作业状态。

恢复负载均衡作业¶

恢复负载均衡作业，请执行命令RECOVER JOB <job_id>。

Note

可以恢复执行失败的作业。
对于停止的作业，Nebula Graph 会判断该作业的开始时间（start time）之后是否有相同类型的失败作业（failed job）或完成作业（finished job），如果有的话，无法恢复停止的作业。例如当有stopped job1 -> finished job2 -> stopped job3时，只能恢复 job3，无法恢复 job1。

迁移分片¶

迁移指定的 Storage 主机中的分片来缩小集群规模，可以使用命令BALANCE DATA REMOVE <ip:port> [,<ip>:<port> ...]。

例如需要迁移192.168.8.100:9779中的分片，请执行如下命令：

nebula> BALANCE DATA REMOVE 192.168.8.100:9779;
nebula> SHOW HOSTS;
+-----------------+------+-----------+----------+--------------+-----------------------+------------------------+-------------+
| Host            | Port | HTTP port | Status   | Leader count | Leader distribution   | Partition distribution | Version     |
+-----------------+------+-----------+----------+--------------+-----------------------+------------------------+-------------+
| "192.168.8.101" | 9779 | 19669     | "ONLINE" | 15           | "basketballplayer:15" | "basketballplayer:15"  | "3.1.0-ent" |
| "192.168.8.100" | 9779 | 19669     | "ONLINE" | 0            | "No valid partition"  | "No valid partition"   | "3.1.0-ent" |
+-----------------+------+-----------+----------+--------------+-----------------------+------------------------+-------------+

Note

该命令仅迁移分片，不会将 Storage 主机从集群中删除。删除 Storage 主机请参见管理 Storage 主机。

均衡 leader 分布¶

用户可以使用命令BALANCE LEADER均衡 leader 分布。

示例¶

nebula> BALANCE LEADER;

用户可以执行SHOW HOSTS检查结果。

nebula> SHOW HOSTS;
+------------------+------+-----------+----------+--------------+-----------------------------------+------------------------+---------+
| Host             | Port | HTTP port | Status   | Leader count | Leader distribution               | Partition distribution | Version |
+------------------+------+-----------+----------+--------------+-----------------------------------+------------------------+---------+
| "192.168.10.100" | 9779 | 19669     | "ONLINE" | 4            | "basketballplayer:3"              | "basketballplayer:8"   | "3.1.0" |
| "192.168.10.101" | 9779 | 19669     | "ONLINE" | 8            | "basketballplayer:3"              | "basketballplayer:8"   | "3.1.0" |
| "192.168.10.102" | 9779 | 19669     | "ONLINE" | 3            | "basketballplayer:3"              | "basketballplayer:8"   | "3.1.0" |
| "192.168.10.103" | 9779 | 19669     | "ONLINE" | 0            | "basketballplayer:2"              | "basketballplayer:7"   | "3.1.0" |
| "192.168.10.104" | 9779 | 19669     | "ONLINE" | 0            | "basketballplayer:2"              | "basketballplayer:7"   | "3.1.0" |
| "192.168.10.105" | 9779 | 19669     | "ONLINE" | 0            | "basketballplayer:2"              | "basketballplayer:7"   | "3.1.0" |
+------------------+------+-----------+----------+--------------+-----------------------------------+------------------------+---------+

Caution

在 Nebula Graph 3.1.3 中，Leader 切换会导致短时的大量请求错误（Storage Error E_RPC_FAILURE），处理方法见 FAQ。

最后更新: March 7, 2023