Linux System Admins Blog

It was an issue reported by our developer as she’s having trouble getting the correct parameters for video conversion using ffmpeg. The problem is the scratchy sound when the conversion is done on our server (CentOS). So she tried it on local (Windows) using Pazera Converter and loaded the same parameters used on the server and got the desired result.

We checked the Ffmpeg versions, and on local we have SVN-r15451 while the server have SVN-r14991. So we upgraded our Ffmpeg on the server to the latest (at this time SVN-r19313) and this solved our problem. I’m not sure what version of ffmpeg have this fix but atleast it should be SVN-r15451 and up.

You can tell the difference from the sample videos (first 5 seconds) below – both were encoded using the same parameters.
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Yesterday I received new installation request from developers to install ApacheSolr module for Drupal. Check this link for more details on Apache Solr Search Integration. Since this is new to me I spent some time on searching and doing test installations. To make it short below is my setup on our shared hosting server running CentOS with Cpanel.

Type: Multi-core (for possible use on other Drupal sites)
Java Servlet Container: Jetty (built-in on Solr)
Drupal version: 6
Java: 1.6

I based this guide plainly from this Drupal  page, and I made this summary for my own future reference.

Process:

You need to have the Java installed first.
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Here’s my first try working with Amazon Web Services. Covered tasks are the following:
- getting familiar with AWS, specially EC2 and S3.
- working with EC2 instance using CentOS image – search, start/stop, and do some customization of an instance
- create AMIs (private) and start instance from it.
- S3 buckets – upload files.

I based my instructions on previous post on Howto Get Started With Amazon EC2 API Tools, so I won’t give details on some steps. And this post will cover mainly the steps taken to complete my objectives above.
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In this guide i will provide the steps in moving Drupal sites with CiviCRM – with Drupal and CiviCRM in one or separate databases. I will outline the steps and sample commands but won’t give much details, so feel free to ask if you need any clarifications. Also, refer to my previous guide on “HowTo Duplicate or Copy Drupal Site” for detailed instructions, commands, and sample shell scripts.

Moving Files:

• Copy Drupal file and preserve mode (ownerships, permissions, etc)
  Example: cp -rp drupal_source drupal_destination
  Review your directory permissions on sites/default/files, sites/default/files/civicrm, and other directories.

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We recently came across a problem with Cacti and the MySQL counters. For those of you who don’t know how to integrate MySQL statistics into Cacti have a look at this: http://code.google.com/p/mysql-cacti-templates/. These templates are a great way to gain some insight into how your MySQL database servers perform. The templates are actually PHP pages that query the databases through a variety of commands like SHOW STATUS and SHOW ENGINE INNODB STATUS.

The issue that we encountered was that some statistics like the InnoDB buffer pool activity were not displaying anything for one server. Other servers were displaying it just fine and other statistics for that server were also fine.

Among other things the SHOW ENGINE INNODB STATUS command shows deadlock information pertaining to the last deadlock that the InnoDB engine encountered. In some cases this information will be quite extensive and this causes a problem. The output of this command is one giant text field with a limit of 64KB. If the deadlock information is very large other information will get cut off which means certain statistics are lost. The easy fix for this is to restart the database server but in case this is not an option you can always use the innotop utility to wipe the deadlock information by causing a small deadlock.

Finding application memory leaks is important part of keeping systems stable and often very hard to track down. Monitoring application memory consumption can be performed in a few different ways, the easiest is a simple capture of ps and append to log file triggered via cron at desired interval. In this example we will track sshd memory usage via shell script.

#!/bin/bash

PID=`cat /var/run/sshd.pid`
ps -p $PID -o pid -o rss -o %mem -o cmd >> logname
exit

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Running apt-get update gives an error message:

W: GPG error: http://ftp.us.debian.org etch Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 9AA38DCD55BE302B
W: There is no public key available for the following key IDs:
9AA38DCD55BE302B
W: You may want to run apt-get update to correct these problems

A check for this missing key tells us it is for Lenny/5.0 sources which have been introduced to the Debian Archive and all new packages are being signed with this new key.

root@debian:~# gpg --keyserver wwwkeys.eu.pgp.net --list-keys 9AA38DCD55BE302B
pub 4096R/55BE302B 2009-01-27 [expires: 2012-12-31]
uid Debian Archive Automatic Signing Key (5.0/lenny)
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This article is meant to be a quick quide that will introduce the things needed to get you started with Amazon EC2. All this information can be found in the EC2 api docs, and this is not meant to be a replacement of the documentation, just trying to show the things needed in a clear and short form.

Getting Started

First of all you will need one Amazon AWS account and enable the EC2 service; in case you don’t have this already now is the time to create your account. Once you do that you can safely return to this doc

Once you have your account working, while still on the aws site, go and create a new X.509 certificate (under the AWS Access Identifiers page, in the X.509 certificate section near the bottom, click Create New). Once this is done, you will want to download locally the private key file and X.509 certificate.

EC2 API tools

Next you will have to download and install the Amazon EC2 api tools on one system (controlling machine) that will be used to start your EC2 army of servers, and control their usage. You will want to use the latest version (2009-05-15 at this time) as it will support all the features Amazon is offering for the EC2 service.

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This is my first guide in moving Magento site to another site or server. I’ve completed few Magento site transfers as we recently develop and host Magento sites. I also encountered several issues in transferring sites, and searched for different
approaches from other blog/forum sites, such as installing a new Magento instance on destination server. I checked the official Magento guide in moving site but I haven’t tried it yet since my current process works fine. This is similar to my procedures when moving other sites such as Oscommerce, Drupal, Wordpress, etc. I assume you have ssh access to your server.

Database:
– Export/dump source database. You can do it via Phpmyadmin or using mysqldump from command line.
mysqldump -udbuser -pdbpass dbname > filename.sql
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Looking to rewrite all file requests to index?

location / {
root /var/www/nginx-default;
index index.html;
if (!-e $request_filename) {
rewrite . /index.html last;
}
}