Archive for the 'Linux' Category

 

 

May 16 2021

MySQL / PostgreSQL on iSCSI Fail to Start at Boot

Published by under Linux,Mysql,Postgresql

You are hosting Mysql or PostgreSQL data directory on iSCSI disks but the service fails to start at server’s boot. The service does not find the directory. However, you can start the service manually if you log on the server once SSH is available. These are logs for Mariadb but they would be similar for […]

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May 29 2017

Determine Operating System within FTP Session

Published by under AS400,Linux,Networking

The “QUOTE” keyword is essential to allow a user to run system-specific commands on FTP servers (SITE or ALLO for example). These commands do not have to be understood by FTP clients. Most FTP clients send a NOOP – that actually is a dummy packet – to keep the connection up  QUOTE SYST returns the Operating […]

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Oct 06 2016

Processing CSV Files with Perl and Bash

Published by under Linux

Olivier, a friend of mine, had to parse a CSV file and took the opportunity to benchmark the performance of 3 programming languages.   The file contains server names and disks he needs to add up into a hash table in order to get the total disk space for each server. He assumes on his […]

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Sep 13 2015

Apache Reverse Proxy 503 Permission Denied

Published by under Apache,Linux

Apache configured as a reverse proxy forwards requests to a web backend. But your browser throws an enigmatic 503 error: “Service temporarily unavailable”. The first thing I do is looking at the http logs in /var/log/httpd/ssl_error_log, where I am getting some permission issue:(13)Permission denied: proxy: HTTP: attempt to connect to 192.168.1.250:8080 (*) failed You may […]

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Aug 27 2014

LVS: a Free Load-Balancer for Microsoft Exchange

Published by under Linux

Microsoft Exchange traffic can be load-balanced with Microsoft NLB but it requires to set up 4 Exchange servers for the sake that NLB isn’t compatible with (Exchange) cluster. Most Microsoft guys do not recommend it.Among NLB downsides, Exchange services are monitored with a basic ping, meaning the service is considered to be active even if […]

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