For best product performance, increase the number of file
handles above the default of 1024 handles.
About this task
Important: Before you work with your product, increase the number of file
handles. Most products use more than the default limit of 1024 file handles per process. A system
administrator might need to make this change.
Exercise caution when using
the following steps to increase your file descriptors on Linux. If the instructions are not followed
correctly, the computer might not start correctly.
Procedure
To increase your file descriptors:
- Log in as root. If you do not have root access, you will
need to obtain it before continuing.
- Change to the /etc directory
Attention: If you decide to increase the number of file handles in the next step, do
not leave an empty initscript file on your computer. If you do so, your computer will not start
up the next time that you turn it on or restart.
- Use the vi editor to edit the initscript file in the etc directory.
If this file does not exist, type vi initscript to
create it.
- On the first line, type ulimit -n 4096.
The point is that 4096 is significantly larger than 1024, the default
on most Linux computers.
Important: Do not set the number of handles too
high, because doing so can negatively impact system-wide performance.
- On the second line, type eval exec "$4".
- Save and close the file after making sure you have completed
steps 4 and 5.
Note: Ensure that you follow the steps
correctly. If this procedure is not completed correctly, your computer
will not start.
- Optional: Restrict the number of handles available to users or groups by modifying the limits.conf file
in the /etc/security directory. Both SUSE Linux Enterprise Server (SLES) Version 9 and Red Hat Enterprise Linux Version 4.0 have this file by default. If you do not have this file,
consider using a smaller number in step 4 in the previous procedure (for example, 2048). Do this so
that most users have a reasonably low limit on the number of open files that are allowed per
process. If you use a relatively low number in step 4, it is less important to do this. However, if
you set a high number in step 4 earlier and you do not establish limits in the limits.conf file,
computer performance can be significantly reduced.
The following sample limits.conf file restricts all users, and then sets different limits for
others afterwards. This sample assumes that you set handles to 8192 in step 4 earlier.
* soft nofile 1024
* hard nofile 2048
root soft nofile 4096
root hard nofile 8192
user1 soft nofile 2048
user1 hard nofile 2048
Note
that the
* in the preceding example sets the limits for all users first. These
limits are lower than the limits that follow. The root user has a higher number of allowable handles
open, while number available to user1 is between the two. Make sure that you read and understand the
documentation contained in the limits.conf file before making changes.