CentOS Remove Old Kernels

Tonight when upgrading a CentOS Linux server it was noted by YUM that 15MB more disk space was needed to upgrade grub and the kernel itself. Below are four quick steps to verify what kernels are installed, install yum-utils if it is not installed already, delete previous kernels and set YUM to remove old kernels…

Technology Insights

Create And Mount Amazon AWS EC2 EBS Storage To AWS EC2 Linux Instance

Amazon’s AWS products are pretty amazing and allow you to scale with ease for short or long term projects. One thing that can be helpful is mounting extra storage to AWS instances so you have the ability to unmount the storage and mount to different instances in the future. The other benefit is the ability to terminate an Amazon AWS instance and keep the Elastic Block Store (EBS) volume to use on another AWS instance at a later date. Use the directions below to create an Amazon EC2 EBS volume, attach the volume to an Amazon AWS instance, format the volume, and then mount the volume to the instance.

Technology Insights

Remove A Logical Volume From A Logical Volume Group On Linux

While testing various settings and other changes with logical volume groups I had created a test logical volume group that I no longer needed so I needed to remove it. When using the below information be aware that any data contained within the logical volume group will be gone after the logical volume is removed. The information below explains how to first list the current logical volumes with lvscan and then how to remove a specific logical volume with the lvremove command.

Technology Insights

Expand A Partition That Is Part Of A Logical Volume Group While Server Is Running

I recently had a couple new CentOS Linux servers brought online at a colo that a company I work for uses. I had the colo do a very simple install of CentOS so I could handle the details without having to remove a bunch of packages we didn’t need. The servers have two one terabyte drives installed in a RAID 1 configuration which provides us with one terabyte of usable disk space and upon initial configuration had a logical volume group created with three logical volumes. Each of the logical volumes, which included /var, /usr, and /, only had two gigabytes of space so I needed to first expand those logical volumes and later will be creating a large logical volume used for database data. Below I describe expanding already existing logical volumes when there is room to grow in the logical volume group.

Technology Errors

PostgreSQL Not Starting: FATAL: could not write lock file “postmaster.pid”: No space left on device

I have a couple development servers I have been using for testing PostgreSQL configured with walmgr for log shipping. The secondary server stopped working the other day and I finally got a chance to look into it this morning and attempted to restart Postgres via a terminal but it failed. Below I describe how the error was noticed, what was done to troubleshoot PSQL not starting, and what was done to resolve the problem so PostgreSQL would start without issue.