Author: Minto Joseph

vm.swappiness and OOM in RHEL6

The behavior of vm.swappiness was always a bit confusing for novice linux users, as setting vm.swappiness to 0 would not completely disable swapping in the system during a memory crunch. vm.swappiness would only affect the agressiveness of swapping. Following upstream…

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Encrypting sensitive data in puppet using hiera-eyaml

Minto Joseph, Site Reliability Consultant at Pythian, explains how to encrypting sensitive data in puppet using hiera-eyaml.

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Debugging Kibana using Chrome developer tools

Minto Joseph, Site Reliability Consultant at Pythian, details his experience debugging Kibana using Chrome developer tools.

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Nagios Authentication with Active Directory.

  Nagios authentication with Active Directory aligns with user management consolidation policies in most organizations. This post explains how to setup Nagios authentication with Active Directory, while using Apache as web server. mod_authz_ldap is an apache LDAP authorization module. This can…

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fsfreeze in Linux

The fsfreeze command, is used to suspend and resume access to a file system. This allows consistent snapshots to be taken of the filesystem. fsfreeze supports Ext3/4, ReiserFS, JFS and XFS. A filesystem can be frozen using following command: #…

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Using strace to debug application errors in linux

strace is a very useful tool which traces system calls and signals for a running process. This helps a lot while debugging application level performance issues and bugs. Aim of this post is to demonstrate the power of strace in…

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Troubleshooting a Multipath Issue

Multipathing allows to configure multiple paths from servers to storage arrays. It provides I/O failover and load balancing. Linux uses device mapper kernel framework to support multipathing. In this post I will explain the steps taken to troubleshoot a multipath…

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Debugging High CPU Usage Using Perf Tool and vmcore Analysis

There are several tools and technologies available to debug deeper into high CPU utilization in a system; perf, sysrq, oprofile, vmcore, and more. In this post, I will narrate the course of debugging a CPU utilization issue using technologies like perf…

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Some Observations on Puppetrun with Foreman

After joining Pythian I was introduced to several configuration management systems and Puppet was one of them. Foreman is a system management tool which can be integrated with Puppet to manage puppet modules and to initiate puppet runs on hosts…

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Auditing Files in Linux

Stat command in Linux can be used to display a file or a file system status. I came across an issue in RHEL4 where a file’s ‘Change time’ is far ahead than the ‘Modification time’ without a change in uid,…

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