LinuxHostingSupport

The “mptctl” kernel module is required to check the RAID status on a Linux server using “mpt-status” tool.

You may receive “/dev/mptctl: No such device” message OR “Make sure mptctl is loaded into the kernel” while checking the RAID status which indicates that the module is not loaded in the kernel OR the device “/dev/mptctl” is not created.

# mpt-status 
 open /dev/mptctl: No such device 
 Are you sure your controller is supported by mptlinux? 
 Make sure mptctl is loaded into the kernel

To create the mptctl device, execute:

# mknod /dev/mptctl c 10 22

and verify it by

# ls -la 
 /dev/mptctl crw------- 1 root root 10, 220 Apr 12 08:05 /dev/mptctl

Once the device is created, load the module in the kernel using modprobe

# modprobe mptctl

and verify it using lsmod which should list the following modules along with it’s details

# lsmod |grep mptctl 
 mptctl 
 mptbase 
 scsi_mod

Add the module in /etc/rc.modules file to load the module in kernel on every reboot.

modprobe mptctl

Save the file. This will make sure the module is loaded in the kernel on every server reboot.

Once done, you will be able to check the RAID status by executing the ‘mpt-status’ command and it should show something like the following:

# mpt-status
 ioc0 vol_id 0 type IM, 2 phy, 465 GB, state OPTIMAL, flags ENABLED 
 ioc0 phy 1 scsi_id 1 ATA ST3 CC38, 10 GB, state ONLINE, flags NONE 
 ioc0 phy 0 scsi_id 4 ATA ST3 CC38, 10 GB, state ONLINE, flags NONE

We install a SSL certificate on a domain to secure the transaction carried out on a website but sometimes we receive an error message

"Invalid command "SSLEngine", perhaps misspelled or 
 defined by a module not included in the server configuration"

while browsing the website. The error message indicates that the module mod_ssl required to run SSL engine on a CentOS server is missing and needs to be installed.

Install the mod_ssl module using yum

# yum install mod_ssl

Once it is installed, make sure to restart the Apache service

# service httpd restart

You should now be able to browse the website using https.

While compiling ‘mpt-status’ tool with the kernel source, you may receive a ‘linux/compiler.h: No such file or directory’ message.

mpt-status.h:6:28:error: linux/compiler.h: No such file or directory
make: *** [mpt-status] Error 1

The reason is the missing compiler.h header file which isn’t all that necessary. The fix is to edit the mpt-status.h file which is under the extracted directory

# vi mpt-status.h

and remove the line which states

#include <linux/compiler.h>

Save the file and you should be able to compile ‘mpt-status’ using “make” with the kernel source.

The ‘mock’ module is responsible to build the source RPMs (SRPMs) under a chroot environment and uses the ‘mockbuild’ user.

If the mockbuild user does not exist while installing the source RPM, you will receive the ‘Warning: user mockbuild does not exist. using root‘ error message.

In order to fix the warning message, install the ‘mock’ module:

# yum install mock

and create the ‘mockbuild’ user

# useradd -s /sbin/nologin mockbuild

Once done, you should be able to install the required tool under the mockbuild user.

When PHP is not compiled with Mysql, you receive ‘Call to undefined function mysql_connect’ error message on your website

Fatal error: Call to undefined function mysql_connect()
 in filename.php on line xx

In order to fix the issue, install the “php-mysql” package using yum

# yum install php-mysql

Once installed, restart the httpd service

# service httpd restart

To verify if the package is installed properly, execute

# php -i | grep mysql