Increase the maximum number of file descriptors

List the max value of open file descriptors

You can use the following command:

# sysctl fs.file-max


# cat /proc/sys/fs/file-max

Increase the file-max value

# sysctl -w fs.file-max=100000

To make the change permanent:

# vi /etc/sysctl.conf
fs.file-max = 100000

Don’t forget to sysctl -p to reload the setting file.

User level FD limits

Beside the system maximum value, there is also two limits (hard and soft) for user account. You can check theses values using ulimit like this:

# ulimit -Hn
# ulimit -Sn

You can override theses values for a specific user if needed, into the /etc/security/limits.conf file. To get the list of the most greedy process, use this snippet:

lsof +c 15 | awk '{printf("%15s  (%s)\n", $1, $2)}' | sort | uniq -c | sort -rn