Apache Doris 高可用与容灾：构建稳定可靠的数据分析平台
Apache Doris 的 Frontend (FE) 节点主要负责元数据管理、查询解析、查询计划生成和查询调度等。在高可用架构中，FE 节点通常采用 Master-Observer 模式来实现高可用性。
FE 节点角色与职责
- Master: 负责处理所有写操作，管理元数据，进行负载均衡
- Observer: 仅处理读请求，不参与选举，与 Master 保持数据同步
- Follower: 参与选举，处理读写请求
FE 高可用配置步骤
```
# 设置元数据存储目录
METADATA_STORAGE_ROOT = /path/to/metadata
# 设置节点角色为 Observer
ROLE = OBSERVER
# 设置 Master 节点地址
MASTER_ADDRESSES = master_ip:port1,master_ip:port2
# 设置选举超时时间
ELECTION_TIMEOUT_MS = 5000
```
```
sh start_fe.sh –daemon
```
```sql
SHOW PROC '/cluster';
```
检查各节点状态是否正常，确保 Observer 已成功加入集群。
FE 高可用关键机制
Doris FE 的高可用主要基于以下机制：
- 选举机制：当 Master 节点宕机时，Follower 节点会进行选举，选出新 Master
- 元数据同步：所有 FE 节点实时同步元数据，确保元数据一致性
- 读写分离：Observer 节点分担读压力，Master 专注于处理写操作
Backend (BE) 节点是 Doris 的数据存储节点，负责数据存储和查询执行。BE 副本机制是 Doris 高可用的核心保障。
BE 副本机制原理
Doris 使用多副本存储机制来确保数据高可用，默认情况下每个数据块有 3 个副本，分布在不同的 BE 节点上。
副本状态管理
Doris 将副本状态分为以下几种：
| OK | 副本正常 | 无需处理 |
| COPIED | 副本已复制 | 可转为 OK |
| DECOMMISSIONED | 节点下线 | 自动修复副本 |
| MISSING | 副本丢失 | 触发修复流程 |
| ERROR | 副本错误 | 需要人工干预 |
BE 副本配置与管理
在 be.conf 中设置：
```
# 默认副本数
default_replication_num = 3
```
```
# 存储根路径
storage_root_path = /path/to/storage1
# 冷热数据分离
storage_root_path = /path/to/hot1:/path/to/cold1
```
Doris 会自动检测副本状态，并在副本不足时自动复制：
```sql
— 手动触发副本修复
ALTER TABLE TABLE_NAME SET ("replication_num" = 3);
— 查看复制任务状态
SHOW REPAIR TABLE FROM db_name;
```
BE 故障恢复流程
当 BE 节点发生故障时，Doris 会自动执行以下流程：
跨集群备份是保障数据安全的重要手段，Doris 提供了完整的备份恢复机制。
备份原理与策略
Doris 备份基于时间点快照，支持全量和增量备份。备份可以存储在本地的文件系统，也可以存储在远程对象存储服务中。
| 全量备份 | 备份整个数据库 | 定期全量备份，数据量较小 |
| 增量备份 | 仅备份变化数据 | 频繁备份，数据量大 |
| 快照备份 | 基于时间点快照 | 需要精确恢复到某个时间点 |
跨集群备份配置
```
# 在 fe.conf 中配置
REPOSITORY_FOR_BACKUP = hdfs://namenode:8020/doris_backup
# 或使用云存储
REPOSITORY_FOR_BACKUP = s3://bucket/doris_backup
```
```sql
CREATE REPOSITORY repo1
WITH BROKER 'broker_name'
PROPERTIES ("broker_username" = "user", "broker_password" = "password");
```
备份与恢复流程
下面是 Doris 跨集群备份与恢复的流程图：
#publish-mermaid-0-1790588890663{font-family:\”trebuchet ms\”,verdana,arial,sans-serif;font-size:16px;fill:#333;}@keyframes edge-animation-frame{from{stroke-dashoffset:0;}}@keyframes dash{to{stroke-dashoffset:0;}}#publish-mermaid-0-1790588890663 .edge-animation-slow{stroke-dasharray:9,5!important;stroke-dashoffset:900;animation:dash 50s linear infinite;stroke-linecap:round;}#publish-mermaid-0-1790588890663 .edge-animation-fast{stroke-dasharray:9,5!important;stroke-dashoffset:900;animation:dash 20s linear infinite;stroke-linecap:round;}#publish-mermaid-0-1790588890663 .error-icon{fill:#552222;}#publish-mermaid-0-1790588890663 .error-text{fill:#552222;stroke:#552222;}#publish-mermaid-0-1790588890663 .edge-thickness-normal{stroke-width:1px;}#publish-mermaid-0-1790588890663 .edge-thickness-thick{stroke-width:3.5px;}#publish-mermaid-0-1790588890663 .edge-pattern-solid{stroke-dasharray:0;}#publish-mermaid-0-1790588890663 .edge-thickness-invisible{stroke-width:0;fill:none;}#publish-mermaid-0-1790588890663 .edge-pattern-dashed{stroke-dasharray:3;}#publish-mermaid-0-1790588890663 .edge-pattern-dotted{stroke-dasharray:2;}#publish-mermaid-0-1790588890663 .marker{fill:#333333;stroke:#333333;}#publish-mermaid-0-1790588890663 .marker.cross{stroke:#333333;}#publish-mermaid-0-1790588890663 svg{font-family:\”trebuchet ms\”,verdana,arial,sans-serif;font-size:16px;}#publish-mermaid-0-1790588890663 p{margin:0;}#publish-mermaid-0-1790588890663 .label{font-family:\”trebuchet ms\”,verdana,arial,sans-serif;color:#333;}#publish-mermaid-0-1790588890663 .cluster-label text{fill:#333;}#publish-mermaid-0-1790588890663 .cluster-label span{color:#333;}#publish-mermaid-0-1790588890663 .cluster-label span p{background-color:transparent;}#publish-mermaid-0-1790588890663 .label text,#publish-mermaid-0-1790588890663 span{fill:#333;color:#333;}#publish-mermaid-0-1790588890663 .node rect,#publish-mermaid-0-1790588890663 .node circle,#publish-mermaid-0-1790588890663 .node ellipse,#publish-mermaid-0-1790588890663 .node polygon,#publish-mermaid-0-1790588890663 .node path{fill:#ECECFF;stroke:#9370DB;stroke-width:1px;}#publish-mermaid-0-1790588890663 .rough-node .label text,#publish-mermaid-0-1790588890663 .node .label text,#publish-mermaid-0-1790588890663 .image-shape .label,#publish-mermaid-0-1790588890663 .icon-shape .label{text-anchor:middle;}#publish-mermaid-0-1790588890663 .node .katex path{fill:#000;stroke:#000;stroke-width:1px;}#publish-mermaid-0-1790588890663 .rough-node .label,#publish-mermaid-0-1790588890663 .node .label,#publish-mermaid-0-1790588890663 .image-shape .label,#publish-mermaid-0-1790588890663 .icon-shape .label{text-align:center;}#publish-mermaid-0-1790588890663 .node.clickable{cursor:pointer;}#publish-mermaid-0-1790588890663 .root .anchor path{fill:#333333!important;stroke-width:0;stroke:#333333;}#publish-mermaid-0-1790588890663 .arrowheadPath{fill:#333333;}#publish-mermaid-0-1790588890663 .edgePath .path{stroke:#333333;stroke-width:1px;}#publish-mermaid-0-1790588890663 .flowchart-link{stroke:#333333;fill:none;}#publish-mermaid-0-1790588890663 .edgeLabel{background-color:rgba(232,232,232, 0.8);text-align:center;}#publish-mermaid-0-1790588890663 .edgeLabel p{background-color:rgba(232,232,232, 0.8);}#publish-mermaid-0-1790588890663 .edgeLabel rect{opacity:0.5;background-color:rgba(232,232,232, 0.8);fill:rgba(232,232,232, 0.8);}#publish-mermaid-0-1790588890663 .labelBkg{background-color:rgba(232, 232, 232, 0.5);}#publish-mermaid-0-1790588890663 .cluster rect{fill:#ffffde;stroke:#aaaa33;stroke-width:1px;}#publish-mermaid-0-1790588890663 .cluster text{fill:#333;}#publish-mermaid-0-1790588890663 .cluster span{color:#333;}#publish-mermaid-0-1790588890663 div.mermaidTooltip{position:absolute;text-align:center;max-width:200px;padding:2px;font-family:\”trebuchet ms\”,verdana,arial,sans-serif;font-size:12px;background:hsl(80, 100%, 96.2745098039%);border:1px solid #aaaa33;border-radius:2px;pointer-events:none;z-index:100;}#publish-mermaid-0-1790588890663 .flowchartTitleText{text-anchor:middle;font-size:18px;fill:#333;}#publish-mermaid-0-1790588890663 rect.text{fill:none;stroke-width:0;}#publish-mermaid-0-1790588890663 .icon-shape,#publish-mermaid-0-1790588890663 .image-shape{background-color:rgba(232,232,232, 0.8);text-align:center;}#publish-mermaid-0-1790588890663 .icon-shape p,#publish-mermaid-0-1790588890663 .image-shape p{background-color:rgba(232,232,232, 0.8);padding:2px;}#publish-mermaid-0-1790588890663 .icon-shape .label rect,#publish-mermaid-0-1790588890663 .image-shape .label rect{opacity:0.5;background-color:rgba(232,232,232, 0.8);fill:rgba(232,232,232, 0.8);}#publish-mermaid-0-1790588890663 .label-icon{display:inline-block;height:1em;overflow:visible;vertical-align:-0.125em;}#publish-mermaid-0-1790588890663 .node .label-icon path{fill:currentColor;stroke:revert;stroke-width:revert;}#publish-mermaid-0-1790588890663 .node .neo-node{stroke:#9370DB;}#publish-mermaid-0-1790588890663 [data-look=\”neo\”].node rect,#publish-mermaid-0-1790588890663 [data-look=\”neo\”].cluster rect,#publish-mermaid-0-1790588890663 [data-look=\”neo\”].node polygon{stroke:#9370DB;filter:drop-shadow(1px 2px 2px rgba(185, 185, 185, 1));}#publish-mermaid-0-1790588890663 [data-look=\”neo\”].swimlane.cluster rect{filter:none;}#publish-mermaid-0-1790588890663 [data-look=\”neo\”].node path{stroke:#9370DB;stroke-width:1px;}#publish-mermaid-0-1790588890663 [data-look=\”neo\”].node .outer-path{filter:drop-shadow(1px 2px 2px rgba(185, 185, 185, 1));}#publish-mermaid-0-1790588890663 [data-look=\”neo\”].node .neo-line path{stroke:#9370DB;filter:none;}#publish-mermaid-0-1790588890663 [data-look=\”neo\”].node circle{stroke:#9370DB;filter:drop-shadow(1px 2px 2px rgba(185, 185, 185, 1));}#publish-mermaid-0-1790588890663 [data-look=\”neo\”].node circle .state-start{fill:#000000;}#publish-mermaid-0-1790588890663 [data-look=\”neo\”].icon-shape .icon{fill:#9370DB;filter:drop-shadow(1px 2px 2px rgba(185, 185, 185, 1));}#publish-mermaid-0-1790588890663 [data-look=\”neo\”].icon-shape .icon-neo path{stroke:#9370DB;filter:drop-shadow(1px 2px 2px rgba(185, 185, 185, 1));}#publish-mermaid-0-1790588890663 :root{–mermaid-font-family:\”trebuchet ms\”,verdana,arial,sans-serif;}
准备备份
创建备份任务
系统快照元数据
传输数据到远程存储
验证备份完整性
完成备份
启动恢复过程
选择备份源
创建恢复任务
下载备份数据
加载到目标集群
验证恢复数据
完成恢复
备份完成
恢复完成
备份与恢复命令
```sql
BACKUP DATABASE db_name TO repo1;
```
```sql
SHOW BACKUP;
```
```sql
RESTORE FROM repo1 backup_id;
```
下面是一个简单的 Bash 脚本，用于定期执行 Doris 备份：
#!/bin/bash
# 设置变量
BACKUP_DATE=$(date +%Y%m%d)
BACKUP_PATH="/data/doris_backup/$BACKUP_DATE"
REPO="repo1"
# 创建备份目录
mkdir -p $BACKUP_PATH
# 执行 Doris 备份
mysql -h<fe_host> -P<port> -u<user> -p<password> -e "
BACKUP DATABASE db_name TO $REPO WITH ('backup_format' = 'json');
"
# 等待备份完成
mysql -h<fe_host> -P<port> -u<user> -p<password> -e "
SHOW BACKUP;
" | grep -q "FINISHED"
# 检查备份结果
if [ $? -eq 0 ]; then
echo "Backup completed successfully"
# 压缩备份文件
tar -czf $BACKUP_PATH.tar.gz $BACKUP_PATH
rm -rf $BACKUP_PATH
else
echo "Backup failed" >&2
exit 1
fi
注意事项：
