APC (Alternative PHP Cache) come with a nice script (apc.php) that will sort and show you the memory usage and hit ratio of pages cached into APC memory. Do these easy steps to set this up on your Web server. Copy the script from APC folder into a vHost on your Web server (this example… Read More »
Since CentOS/RedHat Enterprise Linux 6, “mod_file_cache”, commonly referred as “MMapFile” too is no longer provided with Apache binary. File Cache module statically map file pages into memory. This module is still experimental according to Apache documentation, which may explain why it’s not included, even though it was included in CentOS/RHEL5. You may get the following… Read More »
Found this error in your Web site Apache error logs? PHP Warning: require_once(): Unable to allocate memory for pool. This is actually caused by APC (Alternative PHP Cache). The allocated memory limit for APC has been reached and no additional PHP script can be cached anymore. The symptoms on your Web site for such error… Read More »
I recently observed this strange behavior from a Dell PowerEdge 2950 with PERC 6/i RAID controller. – One drive member from a RAID-5 array was failed – I pulled out the defective drive and pop in a brand new drive – Strangely, it did not started to sync and after a few moment, the drive… Read More »
Here is a quick reminder about the default username and password for Dell DRAC out-band server management : Username : root Password : calvin
UUIDs (Universal Unique Identifier) for network interface card can be generated using the following command : uuidgen <DEVICE> Example : uuidgen eth0 Then you can add it to your NIC config file (assuming your interface is eth0) : /etc/sysconfig/network-scripts/ifcfg-eth0 Add/modify the following : UUID=<uuid>
Did your Qmail server failed to receive a message including an attachment and showing this output in the SMTP logs? policy_check: remote sender@domain.tld -> local recipient@domain.tld (UNAUTHENTICATED SENDER) policy_check: policy allows transmission qmail-smtpd: qq soft reject (mail server temporarily rejected message (#4.3.0)): MAILFROM:<sender@domain.tld> RCPTTO:recipient@domain.tld tcpserver: end 0000 status 000 In this particular case, the version… Read More »
It’s possible to tell the kernel of your Xen guest VM to synchronize or not the clock with the physical host machine. There are numerous reason why you would or not to use this feature (such as your guest VM is behind or forward the clock over time). To find out the current setting, simply… Read More »
VMware ESXi management IP/vSphere connectivity might become suddenly unavailable over the time or after replacing the network interface card. This can be easily resolved by removing the vmnic port groupe for the management network and add it back again to the vSwitch. You will need direct console access to the ESX shell to perform these… Read More »
Here is a quick how to force your network interface speed and duplex on RHEL/CentOS Linux. Make sure you have the network tools installed : yum install ethtool net-tools To apply the configuration without having to restart the network service or reboot your system, simply do this command with your settings : ethtool -s <INTERFACE>… Read More »