For best product performance, increase the number of file
handles above the default of 1024 handles.
Before you begin
Make sure that you have root access. You might need to be
an administrator to change the file handle limit.
About this task
Important: Before you work with
your product, increase the number of file handles. Most IBM® Rational® products
use more than the default limit of 1024 file handles for each process.
Be
careful when you increase your file descriptors on Linux. If you do not follow the instructions
correctly, your computer might not start correctly.
Procedure
- Log in as root.
- Change to the etc directory.
Attention: If you 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 after
you turn it off.
- 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.
- Set the limit to 4096: on the first line, type ulimit
-n 4096.
Important: Do not set
the number of handles too high, because doing so can negatively affect
system-wide performance.
- On the second line, type eval exec "$4".
- Make sure that you have completed steps 4 and 5; then,
save and close the file.
Note: Be sure to follow the steps
correctly. If this procedure is not completed correctly, your computer
will not start.
- Optional: Restrict
the number of handles that are 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, for example, 2048. By using a smaller number, most users will
have a reasonably low limit on the number of open files that are allowed
for each process. If you use a relatively low number in step 4, it
is less important to modify the limits.conf file.
However, if you set a high number in step 4 and you do not establish
limits in the limits.conf file, computer performance
can be reduced.
Example
The following sample
limits.conf file
restricts all users, and then sets different limits for others. In
this sample, the handles were set to 8192.
* soft nofile 1024
* hard nofile 2048
root soft nofile 4096
root hard nofile 8192
user1 soft nofile 2048
user1 hard nofile 2048
The asterisk (
*)
in the 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 higher and lower numbers. Before you change the
limits.conf file,
make sure that you read and understand the documentation contained
in that file.