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AIX > Tips & Techniques > Miscellaneous

How to Hire an AIX Systems Administrator

AIX Administrator

I’m often asked by colleagues if I know of anyone that is looking for an AIX systems administrator. Hiring an admin can be a daunting task, even for experienced IT managers. Where do you find the right people and when you do, what kinds of questions you ask? What types of skills are you looking for and what type of training would you want them to have in their repertoire?

The Search

While there are many job-board portals, I’ve always narrowed my focus to a select few. Both Dice and are two of the better sites. While I prefer Dice, Indeed has become probably the largest job board and it has the added perk of being free for recruiters.

You should also use LinkedIn because it’s so intuitive. While you can use the business social networking site in the same way you use more standard job boards, you can also find out a lot about prospective candidates from looking at their profiles. Everyone should have Linkedin today, and if they don’t, I would question why.

After going through resumes and preliminary narrowing my search to 8-12 candidates, I would typically phone screen about six to eight candidates. I like to do these myself, before engaging feedback from my team. It’s during the phone screen that I’ll find out if they have really AIX admin material. The candidates we bring on site for an in-person interview should all know their stuff. I’ll create an Excel spreadsheet to track their performance and after completing the 20 minutes phone screen sessions, I’ll bring the top three candidates back for an on-site interview. I’ll also have knowledge of their verbal communicative skills, which is important unless the position is strictly related to writing shell scripts.

During the actual phone screen, I will shoot out dozens of questions, because I want to know what they know in a short period of time, maximizing what I can in those 20 minutes. There are three categories that I will focus on during the phone screen: basic UNIX fundamentals, AIX specific questions and virtualization. I may even throw in a PowerHA/HACMP question or two. What follows is a deeper dive into some of the questions that I may ask.

Basic Unix Fundamentals

  1. How do you search for a file in a filesystem? One way is to use grep.

  2. ls – ltr | grep testfile or find ./ -depth | grep testfile

  3. How do you check your default gateway?

  4. # netstat – rn. This may also lead me to other networking questions, such as how to view information about your adapter? # ifconfig – a. I might even ask them how to change adapter information using ifconfig and wait for their correct syntax answer. I want them to give me the real answer, which in AIX would be to NEVER to change your adapter using ifconfig because it won’t save the changes on a reboot.

  5. Since we’re talking reboot: How do you boot or reboot a system? There are many ways, but I want to hear some version of # Shutdown – Fr. They can alternatively use init or reboot, but shutdown is safer. If they mention init. I will ask them about inittab. The inittab file provides a method of starting services on a system boot. If I’m on the subject, I’ll also ask them how to refresh the inittab file. The correct answer is Kill – HUP 1. What about editing? While you can use vi, if you make a mistake, it can cause your system to become inoperable. I want to hear candidates say, “I like to be careful and use the chitab command.” I would even be happy to hear, “I like to make a copy beforehand.” I may also ask them some questions about how they edit files. Of course, I want to hear them talk about vi. While reviewing vi, I may ask them how they can search for a word in a file or how they save a file, just to get an understanding of how good they are with the tool. A UNIX admin needs to know vi. They should also know the basics of shell scripting, so I’ll ask them a little about what shells they have used to script.
  6. I like to ask a few questions about permissions—both how to see them and how to change them. I may ask specifically how to make a file only (filex) readable to the user. The answer would be # chmod 600 filex.
  7. How do you back up your systems? Please tell me you have used # mksysb.

AIX Specific Questions

  1. What is the ODM and what is it used for? I like to throw in this question, because it gives me an understanding of how much this person has used AIX. The Object Data Manager is used while installing and configuring hardware (devices) and software and provides all kinds of information. Most AIX admins have had to run commands such as # odmget or # odmdelete, and I like an old-school AIX admin who has this kind of experience.
  2. How do you add space to a filesystem? Please don’t say I use SMIT. That is not the answer we want to hear. When your f/s is out of space, you need to take immediate action, and there is nothing quicker than adding space to a f/s. I will ask, how do you increase the size of your f/s by 4 GB. Here is the answer, as this increases it by 8192000 512-byte blocks.
  3. # chfs – a size =+8192000 /u/test. 
    I like to ask some basic questions about volume groups and physical volumes. How do you see the physical volumes in a volume group. # lspv testvolvgrp, or how do you view logical volumes - # lslv lvol1. Before candidates get into the detailed stuff in AIX, I want to know if they can handle the basics.


As most AIX administrators know today, you can’t be an AIX admin without knowing about virtualization. I would start with VIO servers. If they can’t tell you their purpose, I wouldn’t go any further with the interview. I’d like them to say that VIO servers allow LPARs to share storage and network resources. They need to communicate that they know basic concepts. Sure, I’d love it if they could tell me the entire syntax of # lsmap or how to set up N-Port ID Virtualization (NPIV), but I’d like to hear them talk about basic concepts first. Depending on the answers I get, I’ll fire back with additional questions. I always advise people to never talk about anything, unless you are sure you can answer questions about it proficiently. Don’t indiscriminately talk about inodes unless you can answer the question, “what is an inode?”

I also will usually talk about how to create a VIO LPAR, only because I want them to tell me a little about their experience with HMCs. I might even ask them questions about upgrading HMCs or what OS an HMC runs on top of. If I’m in the mood, perhaps I’ll ask them if they have ever used Live Partition Mobility or AIX WPARs.

On-site Interview Questions

During the on-site interview, from a technical standpoint, I want to get a better understanding of the person’s ability to work issues and problem solve. Here’s one scenario:

What do you do if your find your system is running unusually slow today? I’d like to hear them talk about how they communicate with the business and what their action plan is. Sometimes, I will throw in a trick question. I’ll ask how to kill an Oracle process if they determine the system is too slow. If they say kill -9, that may be the logical answer, but you never want to start a kill with -9, as that will not stop the process in an orderly fashion. I would prefer if they said kill – 1. Kill – 9 is not ignorable and signals the process to quit immediately. Really, I don’t want them to kill jobs at the command line, I would prefer that the application somehow does this. Just because you identify the problem doesn’t mean you must take action on it immediately. You can bring down your entire application by haphazardly using kill.

Regarding performance, I want to hear them talk about the commands they use to ascertain overall performance and how they might go about troubleshooting a performance issue. I want to hear them talk about top, or nmon or vmstat.

I will also ask candidates about the worst mistake they’ve ever made. If they say they have never made one, I know they’re not working complex systems or projects, they’re newbies or they’re being deceitful. I’m not interested in hiring anyone with these traits.

Skills and Training Questions

When I speak with prospective candidates, I’m usually looking for leadership skills. I like to hire a sysadmin who not only knows his stuff, but also can lead a server consolidation effort, a major upgrade of some kind or has experience as a team lead in a production environment. I also prefer someone that has skills working as part of a larger team, rather than someone that was part of a very small team (or even a team of one) because people who have worked on larger teams have more experience working with others and know how to work as part of a team.

Communicative skills are also important to me, and I’m not just talking about verbal communications. I like someone that knows how to write a project plan or has written some technical documentation or even a whitepaper.

What else do I like? I like to hear that candidates are members of user groups. Maybe that’s because I used to run an AIX user group, but I feel that shows a certain level of commitment. Training is also important, because while nothing replaces real life situations, taking courses (and possible certification) shows a high level of commitment to the platform. IBM offers a variety of training classes, and if candidates tell me that they’ve attended an IBM Systems Technical University event, that’s a huge plus for me. for me, that is a huge plus. For a technical nerd, there’s no better way to learn.

What kind of advice would I offer to prospective candidates? Before you go into an interview, prepare for it. I don’t care if you’ve been an AIX admin for 20 years, brush up on the basics and relate them to your resume. If it’s on your resume, I will assume that you know it or did it and will ask you about it. With preparation comes confidence, and with confidence comes a second interview—and ultimately an offer.

Ken Milberg, CATE, PMP, is a diverse IT Professional with 20+ years of experience. He is a Power Systems Champion. Ken is a technology writer and site expert for techtarget and has also been a frequent contributor of content for IBM developerWorks. Ken has also been a freelance writer for IBM Systems Magazine and is a former technical editor. He can be reached at

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