[ https://issues.apache.org/jira/browse/HDFS-7146?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14154252#comment-14154252 ] 

Yongjun Zhang commented on HDFS-7146:
-------------------------------------

Or I can modify the initialization part to only create entry for  numerical names, so to minimize the size of the map, assuming numerical names are the only ones that can't be found by incremental commands. If this assumption is not true, then there is some risk that the fix would break stuff that used to work. What do you think Brandon? Thanks.






> NFS ID/Group lookup requires SSSD enumeration on the server
> -----------------------------------------------------------
>
>                 Key: HDFS-7146
>                 URL: https://issues.apache.org/jira/browse/HDFS-7146
>             Project: Hadoop HDFS
>          Issue Type: Bug
>          Components: nfs
>    Affects Versions: 2.6.0
>            Reporter: Yongjun Zhang
>            Assignee: Yongjun Zhang
>         Attachments: HDFS-7146.001.patch
>
>
> The current implementation of the NFS UID and GID lookup works by running 'getent passwd' with an assumption that it will return the entire list of users available on the OS, local and remote (AD/etc.).
> This behaviour of the command is advised to be and is prevented by administrators in most secure setups to avoid excessive load to the ADs involved, as the # of users to be listed may be too large, and the repeated requests of ALL users not present in the cache would be too much for the AD infrastructure to bear.
> The NFS server should likely do lookups based on a specific UID request, via 'getent passwd <UID>', if the UID does not match a cached value. This reduces load on the LDAP backed infrastructure.
> Thanks [~qwertymaniac] for reporting the issue.



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