MongoDB启动失败求助：WiredTiger版本不匹配及日志格式问题

环境详情 #

• MongoDB版本：初始为3.6.3，尝试升级至4.0
• 存储引擎：WiredTiger
• 部署方式：Docker运行MongoDB，同时系统安装有未启用的MongoDB实例（此前未容器化时曾使用）
• 操作系统：Debian

问题分解 #

初始权限错误 #

启动时返回权限相关错误：

IllegalOperation: Attempted to create a lock file on a read-only directory: /data/mongodb, terminating
MongoDB could not write to /data/mongodb due to permission issues.
Directory ownership was set to UID 999 (unknown user) and group docker.

已采取的操作 #

修改目录权限为mongodb:mongodb：

sudo chown mongodb:mongodb /data/mongodb -R

权限修复后的WiredTiger版本不匹配错误 #

权限修复后仍无法启动，返回版本不匹配错误：

Assertion: 28595:-31802: WT_ERROR: non-specific WiredTiger error
Version Mismatch Error:
txn-recover: unsupported WiredTiger file version: this build only supports versions up to 2, and the file is version 5: WT_ERROR: non-specific WiredTiger error
MongoDB 3.6.3 only supports WiredTiger file versions up to 2.
WiredTiger files were detected as version 5.
This suggests that at some point, the data files were modified by a newer MongoDB version (4.x or 5.x).

升级至MongoDB 4.0后的日志格式错误 #

升级到4.0版本后出现日志格式不兼容错误：

An unsupported journal format detected - If you are trying to rollback from version 4.0 to 3.6, please re-start a 4.0 binary and cleanly shut it down so that the journal format will be downgraded.
Even after upgrading to MongoDB 4.0, the data files were still incompatible, indicating further issues with the journal format.

当前情况 #

删除日志目录后，重启MongoDB 3.6或4.0仍出现版本不匹配错误；测试多个版本均无法加载数据。

根因分析 #

WiredTiger元数据及日志文件疑似被更高版本MongoDB修改或损坏，MongoDB二进制文件与现有数据文件版本不匹配，导致启动失败。

求助问题 #

1. 有无用户成功在无数据丢失的情况下降级WiredTiger元数据或解决类似版本不匹配问题？
2. 从更高版本MongoDB创建的WiredTiger文件恢复数据有哪些推荐步骤？
3. 是否存在安全的方式从现有文件重建或迁移数据至新MongoDB实例且无全面数据丢失？

内容的提问来源于stack exchange，提问作者Deepak Kumar