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 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
- 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 30000.
The point is that 30000 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.
What to do next
For more information on the ulimit command, see the man page
for ulimit.