Archive for September, 2010

Modified cPanel addons are not allowed message

Sorry modified cPanel addons are not allowed, contact your server admin for more info.

To resolve this issue:
1. Login to the WHM.
2. Click on ‘Tweak Settings’
3. Remove the ticks from the below options:

- Prevent installation of addon scripts not provided by cPanel
- Prevent installation of cPanel addon scripts that have be altered (Turning this off may be useful when testing custom addons.)

This should fix the problem.


cPanel’s DNS clustering

cPanel’s DNS clustering

cPanel’s DNS clustering allows you to synchronize DNS records between multiple cPanel or cPanel DNS ONLY machines. In order to synchronize your DNS records, all machines in the cluster must be running cPanel or cPanel DNS ONLY versions 8.9 or higher.

When configuring your server cluster, it is important to minimize the amount of hops between servers to create the shortest path possible. When possible, you should link webserver server directly to your dns servers or any other servers you wish to update. Each time a DNS zone is modified, the modification will travel down the path to reach each server in the path. The performance of the system is directly proportional to the length of the path.

Synchronize Changes: All changes made on your webserver server will be replicated to any server linked to the webserver in the cluster.
Synchronization is one-way: Changes made on the other server will not be replicated to webserver server unless Synchronize Changes is selected on that server as well.
Standalone: All changes made on webserver server will not replicated to any other server(s).


Optimizing Apache

Optimizing Apache

Apache can be tweaked by changing a few of its settings to make it work faster with respect to the capability your server possess.

Some of the values that can be tweaked in the ‘Global’ section of Apache configuration file (found at /usr/local/apache/conf/httpd.conf) are explained below:


This directive sets the maximum amount of time the server will allow a connection to remain open. The default value of 1200 (20 minutes) is appropriate for most instances.


With this directive set to on, the server will attempt to record the userid of each query to the server. Keep this directive set to off unless you are willing to devote a significant amount of network bandwidth to this function.

MaxSpareServers and MinSpareServers

Apache has several statements to configure the number of clients being handled and the number of child-processes it forks off to deal with those requests. If the machine running the Apache installation is not intended for anything but running Apache, it is generally a good idea to make these numbers as high as possible, but not so high that the machine starts paging memory out to its swap space.


The MaxRequestsPerChild directive sets the limit on the number of requests that an individual child process can handle during its lifetime. After MaxRequestsPerChild requests, the child process will die. If MaxRequestsPerChild is zero, the process will live until the server kills it (because it is no longer needed, which will depend on the value of MinSpareServers and the number of current requests) or until the server itself is stopped.

Apache Memory Usage Restrictions in WHM

Main >> Service Configuration >> Apache Configuration

This function will calculate your apache memory usage based on your memory usage history and set a new memory limit for Apache processes. Limiting each process’ access to memory will increase the stability of your server but may reduce performance slightly. This is a limit for each Apache process, not for all Apache processes combined.

Click the Proceed button to activate this feature

For more information about this feature, see

This will add a line to httpd.conf

#Rlimit added by
RLimitMEM 148015786

Hard Drives going bad, how to get SATA/ATA device information.

# hdparm -tT /dev/sda

Timing cached reads: 582 MB in 2.00 seconds = 290.60 MB/sec
Timing buffered disk reads: 96 MB in 3.05 seconds = 31.49 MB/sec

Harddrives come in three kinds: Sata, Ide, and Scsi. Many type of hardware error will how up under linux if you use the command “dmesg”. In fact, almost any type of hardware error or information will show up there.

If you think your drive may be sub par, or you want to test it, then hdparm is a good command.

[~]# hdparm -tT /dev/sda

Timing cached reads: 270 MB in 2.01 seconds = 134.60 MB/sec
Timing buffered disk reads: 80 MB in 3.07 seconds = 26.10 MB/sec

If the second measurement is under 40MB/sec then you shoud change the drive for your server.

Below is the measurement for a new server.

[~]# hdparm -tT /dev/sda

Timing cached reads: 12252 MB in 2.00 seconds = 6135.69 MB/sec
Timing buffered disk reads: 212 MB in 3.01 seconds = 70.51 MB/sec

Note: SMART allows you to have a good degree of prediction on when the drive will reach its end of life.

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