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https://issues.apache.org/jira/browse/HDFS-7146?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14158913#comment-14158913
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Yongjun Zhang commented on HDFS-7146:
-------------------------------------
Hi [~brandonli],
Thanks for the good info, it's really helpful! I was aware that reverse look up
was happening for numerical name, but I didn't know about command "id". Given
that we have this command, I agree with you that we should use it to avoid full
list load.
Unfortunately there is no corresponding one for group. I think we can mitigate
this by doing lazy full list load upon for group: only do full list load when a
given numerical group name is missing from the cache. Assume that numerical
names are rare, we can largely avoid loading the full list. Does this sound
good to you?
I will try to have a revised version asap. 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, HDFS-7146.002.allIncremental.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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