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Comments and suggestions concerning this book should be mailed to gmourani@videotron.ca © Copyright 1999-2000 Gerhard Mourani and Open Network Architecture ® 71 The file-max file “/proc/sys/fs/file-max” set the maximum number of file-handles that the Linux kernel will allocate. We generally tune this file to improve the number of open files by increasing the value of “/proc/sys/fs/file-max” to something reasonable like 256  for every 4M of RAM we have: i.e. for a machine with 128 MB of RAM, set it to 8192 (128/4=32 32*256=8192). · To adjust the value of file-max to 128 MB of RAM, type the following on your terminal: [root@deep /]# echo "8192" >/proc/sys/fs/file-max NOTE: When you regularly receive from your server, a lot of messages with errors about running out of open files, you might want to raise this limit. The default value is 4096. A file server or web server needs a lot of open files. Add the above commands to the “/etc/rc.d/rc.local” script file and you’ll not have to type it again the next time your server reboots. 7.    The “inode-max” parameter The inode-max file “/proc/sys/fs/inode-max” set the maximum number of inodes handlers. We generally tune this file to improve the number of inodes opened by increasing the “/proc/sys/fs/inode-max” to a value roughly 3 to 4 times (8192*4=32768) the number of opened files we have set to the “file-max” parameter above. This is because the number of opened inodes is at least one per open file, and often much larger for large files. · To adjust the value of inode-max to 128 MB of RAM, type the following on your terminal: [root@deep /]# echo "32768" >/proc/sys/fs/inode-max NOTE: If you regularly run out of inodes, you should increase this value. Don’t forget that the value you enter for the “inode-max” parameter depends of the “file-max” value. A file server or web server needs a lot of opened inodes. Add the above commands to the “/etc/rc.d/rc.local” script file and you’ll not have to type it again the next time your server reboots. 8.    The “ulimit’ parameter Linux itself has a "Max Processes" per user limit. This feature allows us to control the number of processes an existing user on the server may be authorized to have. To improve performance, we can safety set the limit of process the super-user “root” may have to be unlimited. Edit the .bashrc file (vi /root/.bashrc) and add the following line: ulimit -u unlimited You must exit and re-login from your terminal for the change to take effect. To verify that you are ready to go, make sure that when you type as root the command  ulimit -a on your terminal, it shows "unlimited" next to max user processes. [root@deep /]# ulimit -a core file size (blocks)   1000000 data seg size (kbytes)    unlimited file size (blocks) unlimited max memory size (kbytes) unlimited stack size (kbytes) 8192