centoshacker

Quick and Dirty Monitoring Tool

admin — Tue, 23 Feb 2010 10:32:39 +0000

Recently, we needed a simple cron script to record load average, apache server count, existence of lighthttpd and mysql status in a log file every 10 minutes. So following shell script was born: #!/bin/sh httpd_cnt=`ps auxww | grep '/home/apache/bin/httpd' | wc -l` lighthttpd_cnt=`ps auxww | grep 'lighthttpd' | wc -l` mysql_status=`/usr/bin/mysqladmin -u root -pYOUR_DB_PWD status` load=`/bin/cat /proc/loadavg` now=`date "+%m-%d-%Y %H:%M:%S"` today=`date [...]

Stop Lock Files from Locking Your Cron Jobs Upon Unscheduled Reboot

admin — Sun, 27 Sep 2009 15:47:37 +0000

Nobody likes unscheduled reboots but it happens to all of us. Recently, we had all our servers rebooted because our data center’s ATS — a device that switches to UPS power — failed. About 90% of the servers returned to life as usual but a few had cron jobs that got stuck due to previous [...]

Creating a swap partition

admin — Sun, 27 Sep 2009 15:00:49 +0000

Recently our data center had a power issue and rebooted all our servers. In this process, one of the server had an issue with the swap partition (/dev/sda3). So we decided to recreate it as follows: # mkfs -t ext3 /dev/sda3 # mkswp /dev/sda3 1024

Surviving fsck.ext3: Unable to resolve LABEL problem

admin — Sat, 26 Sep 2009 10:39:39 +0000

Due to a forced hard reboot, thanks to the Data Center’s faulty PDU, one of our servers got the blues. After getting Nagios alert, we logged onto it via remote KVM and noticed that it is hanging at the maintenance shell prompt. After logging in as root to the maintenance shell, we noticed that the system [...]

Creating SFTP-only User Accounts to Kill SSH Access

kabir — Sat, 26 Sep 2009 10:30:22 +0000

How to create SFTP-only User Accounts to Kill SSH Access

Tuning Postfix to Fight SPAM a Little Better…

admin — Fri, 26 Jun 2009 16:30:56 +0000

How to tune Postfix to fight SPAM a little better without needing anything like spamassassin.

Running out of disk space even when 20% is free!

admin — Mon, 08 Jun 2009 21:44:33 +0000

Today, we had a panic call from a customer who was hosting a small app on a non-dedicated server environment with us. The app uses a ton of images and was hosted on a box with terabytes of disk space. They called with a message saying that the system is out of disk space. After investigating, [...]

Bringing Email Home Across the Globe

admin — Sun, 24 May 2009 19:59:12 +0000

Bringing Email Home Across the Globe

Mounting DVD ISO Files on CentOS 5.3

kabir — Sun, 24 May 2009 16:08:05 +0000

I often forget all the parameters to mount a DVD on a running system, so here is my blog-reminder: # mount -t iso9660 -o loop /path/to/dvd.iso /mount/point Example: mount -t iso9660 -o loop CentOS-5.3-i386-bin-DVD.iso /mnt/dvd This will mount the CentOS 5.3 DVD iso on /mnt/dvd directory.

Setting up BackupPC on CentOS 5.3

kabir — Wed, 20 May 2009 16:00:09 +0000

We use BackupPC and have a love-hate relationship with it. We love that it works most of the time, and hate that it uses CGI Web interface and also outputs cryptic error messages when backup fails. But never the less, we have not found a better deal so far. Hence we continue to use it. Here [...]