Description of problem:
Method for setting system file descriptor limit is not for RHEL7.

URL:
https://access.redhat.com/documentation/en-US/Red_Hat_Directory_Server/10/html-single/Performance_Tuning_Guide/index.html#file-descriptors

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3. Then increase the maximum number of open files on the system by editing the /etc/security/limits.conf configuration file. Add the following entry:

*        -        nofile        8192

4. Edit the /etc/pam.d/system-auth, and add this entry:

session required pam_limits.so

5. Reboot the machine to apply the changes. 
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I suggest to replace with following:
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3. Then increase the maximum number of open files on the system by editing the /etc/sysconfig/dirsrv.systemd configuration file. Change the following entry:

[Service]
LimitNOFILE=8192

4. Restart the service to apply the changes.
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