There is a problem degrading Namenode（Hadoop3.3.4 relegation hadoop2.7.2）

[尉雁磊 <tr...@163.com>]

我在测试hadoop2.7.2滚动升级hadoop3.3.4之后，进行降级测试，在降级namenode时遇到了问题，报错（附件1所示）

After testing Hadoop2.7.2 rolling upgrade Hadoop3.3.4, I conducted the degradation test. I encountered a problem when degrading Namenode, and an error was reported (as shown in Appendix 1).

 

查阅issuse，找到HDFS-14831和我遇到的问题相似

Check Issuse and find HDFS-14831 similar to the problem I encountered

 

我将https://issues.apache.org/jira/browse/HDFS-14831中提到的commit（https://github.com/lucasaytt/hadoop/commit/8a41edb089fbdedc5e7d9a2aeec63d126afea49f）在hadoop2.7.2合并

I merge the COMMIT（https://github.com/lucasaytt/hadoop/commit/8a41edb089fbdedc5e7d9a2aeec63d126afea49f） mentioned in https://issues.apache.org/jira/browse/HDFS-14831 in Hadoop2.7.2

 

但是降级后的namenode（2.7.2），无法进行写操作，报错（附件2所示）：

However, in the degraded Namenode (2.7.2), write operations cannot be performed and an error is reported (as shown in Appendix 2) :

 

Web页面显示目录的Owner和Group显示为Empty

The Owner and Group of the directory are displayed as Empty on the Web page

 

后续发现2.7.2的PermissionStatusFormat中的GROUP和USER分别为25、23，而3.3.4的为24、24（附件3所示）

Subsequent discovery: GROUP and USER in PermissionStatusFormat in 2.7.2 are 25 and 23, respectively, while those in 3.3.4 are 24 and 24 (as shown in Appendix 3).

 

我在2.7.2中修改GROUP和USER为24、24，可以降级成功

I changed GROUP and USER to 24 and 24 in 2.7.2, which can be degraded successfully

 

是否有人遇到相同问题？

Does anyone else have the same problem?

 

此commit：https://github.com/lucasaytt/hadoop/commit/8a41edb089fbdedc5e7d9a2aeec63d126afea49f是否可以合并至hadoop2.7.2中，是否存在隐患？

This commit：https://github.com/lucasaytt/hadoop/commit/8a41edb089fbdedc5e7d9a2aeec63d126afea49f，Can it be merged into Hadoop2.7.2?   Is there any hidden danger?