For best product performance, increase the number of file
handles above the default setting of 1024 handles.
About this task
Important: Before you work with
your Rational® product,
increase the number of file handles. Most Rational 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 must
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 30000.
The point is that 30000 is significantly larger than 1024, the default
value 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 that 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 the number that is available
to user1 is between the two. Make sure that you read and understand
the documentation that the
limits.conf file contains
before making changes.
What to do next
For more information on the
ulimit command,
see the main page for
ulimit in the Linux documentation.