Adam’s Tech Blog

Endless technology ramblings

Where:
%R = the percentage of disk I/O’s that are reads.
%W= the percentage of disk I/O’s that are writes.
f = 1 for ordinary disks, 2 for mirrored disks, 4 for Raid 5 disks.
Assumes data is distributed evenly across all disk drives.

Using the above formula, here’s the minimum number of disks required to support a random I/O workload, at 1000 IOPS,  80% read, 20% write on 10K RPM disk drives.

Ordinary disks:  (0.8 + 1*0.2)(1000 IOPS)/(125 IOPS/disk)  = 8
Mirrored disks:  (0.8 + 2*0.2)(1000 IOPS)/(125 IOPS/disk)  = 10
Raid 5 disks:      (0.8 + 4*0.2)(1000 IOPS)/(125 IOPS/disk) =  13

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Sometimes, for auditing purposes, it can be useful to look for users and groups which are “orphaned” or have no users/groups associated with them.

Finding Orphaned Users

Use this script to find orphaned users:

   1: USEREXCLUSIONS=( sync shutdown halt operator )

   2: USEREXCLUSIONSNUM=${#USEREXCLUSIONS[@]}

   3:  

   4: for i in `cat /etc/passwd | awk -F : {'print $1'}`; do

   5:  

   6: command=`grep $i":x" /etc/group | wc -l`

   7: if [ $command -lt 1 ]; then

   8:  

   9:         for ((t=0;t<$USEREXCLUSIONSNUM;t++)); do

  10:         look=${USEREXCLUSIONS[${t}]}

  11:                 if [ $i = $look ]; then

  12:                         orphaned=0;

  13:                         break;

  14:                 else

  15:                         orphaned=1;

  16:                 fi

  17:         done

  18:  

  19:         if [ $orphaned -eq 1 ]; then

  20:                 echo $i" is orphaned!"

  21:         fi

  22:  

  23: fi

  24:  

  25: done   

Finding Orphaned Groups

Use this script to find orphaned groups:

   1: GROUPEXCLUSIONS=( sys tty disk mem kmem wheel dip lock users floppy utmp slocate )

   2: GROUPEXCLUSIONSNUM=${#GROUPEXCLUSIONS[@]}

   3:  

   4: for i in `cat /etc/group | awk -F : {'print $1'}`; do

   5:  

   6: command=`grep $i":x" /etc/passwd | wc -l`

   7: if [ $command -lt 1 ]; then

   8:  

   9:         for ((t=0;t<$GROUPEXCLUSIONSNUM;t++)); do

  10:         look=${GROUPEXCLUSIONS[${t}]}

  11:                 if [ $i = $look ]; then

  12:                         orphaned=0;

  13:                         break;

  14:                 else

  15:                         orphaned=1;

  16:                 fi

  17:         done

  18:  

  19:         if [ $orphaned -eq 1 ]; then

  20:                 echo $i" is orphaned!"

  21:         fi

  22:  

  23: fi

  24: done

It’s not common for me to find a tool that’s really useful these days. Especially with the advent of spyware, software has just become too cumbersome for something free to spark my interest. Sure, I’ve used many a screen capture utility but nothing has really stuck out. Co-workers always ask for explanations on how to do things and it can be nice to write up a handy document for repeatable tasks but it’s never really as easy as it should be; until now.

So, What is it?

The application I spoke about was Jing. This application is a spin-off free product of Camtasia (TechSmith) and allows you to capture screenshots and allows you to easily upload them to a specified FTP server for sharing. I really enjoy this concept because it closes the gap between screen capture and presentation. Previously I would have to capture what I was thinking and then open the FTP program, then upload it, then copy and paste the URL… then send it to the person in need. With Jing I just capture, and press one button. The Image/Video (yes, VIDEO) is now on my clipboard and ready for presentation.

What Can It Do?

Jing can capture images and video (up to 5 minutes) and automagically FTP them to your server. Other transport mechanisms are available like Screencast.com, Flickr and simple saving to a file on local storage. The interface is very straight forward and easy to use. On the right you can see how the FTP configuration page looks.

Check out Jing today and see how easy sharing your mind can be!