Quoting "C. Linus Hicks" lhicks@nc.rr.com:

On Wed, 2005-02-23 at 21:50 -0500, Mike Obvious wrote:

...

Hi!

Question from the novice.

I have to permanently increase number of opened files ( ulimit -n 16384 and ulimit -Hn 16384) for some application. I did custom kernel based on

https://www.redhat.com/docs/manuals/enterprise/RHEL-3-Manual/sysadmin-guide/...

...

and application documentation ( written for RH 9), no error during all

makes

...

but I have panic during the boot. ( It's Dell SC1425, dual CPU, 2GB RAM, i686-based kernel).

Is there any other way to do it ?

Look in /etc/security/limits.conf

To keep number of opened files at 16384 do the following

Append this to your /etc/security/limits.conf ==================== * soft nofiles 16384 * soft nofiles 16384 ==================== Append this to your /etc/sysctl.conf =================== fs.file-max = 16384 =================== Type sysctl -p to reread your sysctl.conf file. This will also syntax check your sysctl.conf file for you.

Log out, and log back in to complete this task and reread your environment with the new settings.

Important note: Centos 3.x uses a privelege separated sshd by default. You can disable this functionality if needed in /etc/ssh/sshd_config. Basically, sshd runs as the user connecting to it, instead of root. Since root is the only user who can change ulimit settings, you will be unable set ulimit settings as an unprivelged user in an ssh session. The way to test this is to make the changes above and log in at the console. Typing ulimit -n should work correctly. If you ssh to the server, and type ulimit -n it will show the default (probably 1024). If you su - user and then type ulimit -n it should show the correct number (16384)

Hope this helps.

Barry

This was what I found on the issue.

Barry ==================================================================================

Issue: How do I increase the maximum number of open files on my system?

The current setting for maximum number of open files can be viewed with the command:

ulimit -n

This number indicates the maximum number of files normal users (i.e. non-root) can have open in a single session. Note that for the root user, ulimit -n will sometimes output 1024 even after following the procedure to increase the maximum number of open files. This won't effect root's ability to open large numbers of files, as only normal users are bound by this value.

To increase the maximum number of open files beyond the default of 1024, two changes to the system may be necessary. In these examples, we will increase the maximum number of open files to the arbitrary value of 2048. All changes need to be made by the root user and users will need to log out and log back in before the changes will take effect.

1. Configure the system to accept the desired value for maximum number of open files Check the value in /proc/sys/fs/file-max to see if it is larger than the value needed for the maximum number of open files:

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

If the value isn't large enough, echo an appropriate number into the variable and add the change to /etc/sysctl.conf to make it persistent across reboots. If the number is already larger than the value you wish to use, skip to step 2.

# echo 2048 > /proc/sys/fs/file-max

and edit /etc/sysctl.conf to include the line:

fs.file-max = 2048

2. Set the value for maximum number of open files In the file /etc/security/limits.conf, below the commented line that reads

#<domain> <type> <item> <value>

add this line:

* - nofile 2048

This line sets the default number of open file descriptors for every user on the system to 2048. Note that the "nofile" item has two possible limit values under the <type> header: hard and soft. Both types of limits must be set before the change in the maximum number of open files will take effect. By using the "-" character, both hard and soft limits are set simultaneously.

The hard limit represents the maximum value a soft limit may have and the soft limit represents the limit being actively enforced on the system at that time. Hard limits can be lowered by normal users, but not raised and soft limits cannot be set higher than hard limits. Only root may raise hard limits.

When increasing file limit descriptors, you may want to simply double the value. For example, if you need to increase the default value of 1024, increase the value to 2048 first. If you need to increase it again, try 4096, etc. ==================================================================================

Quoting Mike Obvious mike4mike@gmail.com:

Thanks, Barry.

It helps, but with some questions. I did it from console and from ssh logged as root - the same #ulimit -Hn 1024

But if I do login as a user ( from console or from ssh - the same result) - I will have 16384. su - still 16384.

See (ssh session):

[root@NAFNAF root]# ulimit -Hn 1024 [root@NAFNAF root]# su user1 Password: [user1@NAFNAF root]$ ulimit -n 16384 [user1@NAFNAF root]$ ulimit -Hn 16384 [user1@NAFNAF root]$ su root Password: [root@NAFNAF root]# ulimit -n 16384

So, at this point I not sure how many files will have my application running as root. I put this: echo "ulimit -Hn, -n:" >> /root/ulimit.log ulimit -Hn >> /root/ulimit.log ulimit -n >> /root/ulimit.log at the beginning of the script running my app. And it gave me 1024. Sure I can say in the same script ulimit -n 16384 and it works. Any comments on this?

Mike

On Wed, 23 Feb 2005 21:39:45 -0600, Barry Brimer barry.brimer@bigfoot.com wrote:

...

Quoting "C. Linus Hicks" lhicks@nc.rr.com:

...

On Wed, 2005-02-23 at 21:50 -0500, Mike Obvious wrote:

...

Hi!

Question from the novice.

I have to permanently increase number of opened files ( ulimit -n 16384

and

...

...

...

ulimit -Hn 16384) for some application. I did custom kernel based on

https://www.redhat.com/docs/manuals/enterprise/RHEL-3-Manual/sysadmin-guide/...

...

...

...

and application documentation ( written for RH 9), no error during all

makes

...

but I have panic during the boot. ( It's Dell SC1425, dual CPU, 2GB

RAM,

...

...

...

i686-based kernel).

Is there any other way to do it ?

Look in /etc/security/limits.conf

To keep number of opened files at 16384 do the following

Append this to your /etc/security/limits.conf

• soft nofiles 16384
• soft nofiles 16384

==================== Append this to your /etc/sysctl.conf =================== fs.file-max = 16384 =================== Type sysctl -p to reread your sysctl.conf file. This will also syntax

check

...

your sysctl.conf file for you.

Log out, and log back in to complete this task and reread your environment

with

...

the new settings.

Important note: Centos 3.x uses a privelege separated sshd by default. You

can

...

disable this functionality if needed in /etc/ssh/sshd_config. Basically,

sshd

...

runs as the user connecting to it, instead of root. Since root is the only user who can change ulimit settings, you will be unable set ulimit settings

as

...

an unprivelged user in an ssh session. The way to test this is to make the changes above and log in at the console. Typing ulimit -n should work correctly. If you ssh to the server, and type ulimit -n it will show the default (probably 1024). If you su - user and then type ulimit -n it

should

...

show the correct number (16384)

Hope this helps.

Barry _______________________________________________ CentOS mailing list CentOS@caosity.org http://lists.caosity.org/mailman/listinfo/centos

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!DSPAM:421d7188228711035992961!

Are you testing this via an ssh login?

If so, I also had a problem similar to this, and an ugly kludge that I used was to add the ulimit -n 16384 in the sshd initscript before the various functions() get defined.

As I said,... Kludgy, and hopefully someone here knows a cleaner way (that works). ;-)

On Thu, Feb 24, 2005 at 12:17:30AM -0500, Mike Obvious wrote:

I did it before:

• soft nofile 16384
• hard nofile 16384

in /etc/security/limits.conf, but it doesn't work at all - I still have #ulimit -n 1024 #ulimit -Hn 1024

Any other ideas?

Mike

On Wed, 23 Feb 2005 22:22:13 -0500, C. Linus Hicks lhicks@nc.rr.com wrote:

...

On Wed, 2005-02-23 at 21:50 -0500, Mike Obvious wrote:

...

Hi!

Question from the novice.

I have to permanently increase number of opened files ( ulimit -n 16384 and ulimit -Hn 16384) for some application. I did custom kernel based on

https://www.redhat.com/docs/manuals/enterprise/RHEL-3-Manual/sysadmin-guide/...

and application documentation ( written for RH 9), no error during all makes but I have panic during the boot. ( It's Dell SC1425, dual CPU, 2GB RAM, i686-based kernel).

Is there any other way to do it ?

Look in /etc/security/limits.conf

-- C. Linus Hicks <lhicks at nc dot rr dot com>

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