WordPress website page not loading

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Q: Our wordpress website hosted on Linux + Apache + MySQL. Here the issue is page not loading at all. Have did restart the apache server. Then it worked well for few seconds. Again the page stopped loading. All of my clients have seen server unreachable error. There was no configuration change been done in wordpress site. All of us sudden it happened. How to fix it quickly and make my website available to users? Continue reading “WordPress website page not loading”


Linux – How to fix high I/O wait issue?

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Linux server does not responding to application queries. The performance is too low. Underlying disks or SAN LUN’s are normal. From top output found the I/O wait is too high. But there is no I/O intensive tasks are running. While, How to fix high I/O wait issue? Continue reading “Linux – How to fix high I/O wait issue?”


Linux – delete the LUN and remove traces from OS

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In my previous article explained about how to delete disk from ASM library. In this article will learn to delete the LUN and remove traces from server. This article applicable for deleting ASM disk, standard partitioned disk and LVM physical volume. These steps works well for Redhat and SUSE. Continue reading “Linux – delete the LUN and remove traces from OS”


Linux – upgraded HBA firmware not effective

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How to upgrade FC HBA firmware and drivers properly?

We were in progress of upgrading IBM SAN SVC version.  One of the prerequisite is latest recommended HBA firmware and driver level on host systems. Downloaded and installed the latest firmware & drivers from IBM website. But found server still uses old firmware even after reboot. How to make the new firmware effective? Continue reading “Linux – upgraded HBA firmware not effective”


Network interface name changed to “renamex”

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On VMware virtual machine hot added new virtual network interface (NIC). The newly added network interface is of VMXNET3 type. Initially kernel named the new network interface as “eth0”. Post server reboot network interface device name changed from “eth0” to “rename2”. But the other existing network interface name remains same as “eth1”.

[    3.582159] eth0: NIC Link is Up 10000 Mbpsvmware-suse-guest-vmxnet3-nic
[    3.598345] eth1: NIC Link is Up 10000 Mbps
[    3.741375] udev: renamed network interface eth0 to rename2
[  130.435772] bonding: bond0: Adding slave eth1.

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fix network connection slowness

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Network connection slowness is one of the interesting scenarios I came across. It might help someone.

My application servers are placed in one VLAN. And backup server placed in another VLAN. Since it is LAN bandwidth supposed to be 40-50 Mbps. But the connection between both application and backup server were at ~100KBPs transfer rate. I have checked router, firewall and VLAN settings. Everything looks good. No ware bandwidth limit identified.  So, how do I fix network connection slowness issue? Continue reading “fix network connection slowness”


Restrict ‘su’ command – SUSE

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By default all user has access to command “su”. This command allows login to other user from current shell. Of course they should know target user password. The problem is you cannot have control/log of users once they switched successfully. What happens if the user by chance able to switch as root?

Desired secure method to switch across user is restrict “su” command. Enforce them to use “sudo” instead. Continue reading “Restrict ‘su’ command – SUSE”


Avoid cluster filesystem entering read-only mode

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Linux kernel remounts the filesystem into read-only mode whenever it cannot process I/O. This might happen due to various reasons such as disk failure, SAN connectivity issue, disk with bad blocks etc. On Virtual machine and SAN based storage environment even the high latency may lead to I/O hung and result in read-only mode. Continue reading “Avoid cluster filesystem entering read-only mode”