Q&A: Using VAMI and vimptop To Monitor Your VCSA
Tom Fenton shares some of the Q&As that went on after his VMworld session where he discussed using the vCenter Management Interface and vimtopo to do real-time monitoring of the health of a vCenter Server Appliance.
At VMworld this year I had a chance to deliver the session Ensure Maximum Uptime and Performance of Your vCenter Server Appliance [VIN1293BU] in which I outlined how to use the vCenter Management Interface (VAMI) and vimtop to do real-time monitoring of the health of a vCenter Server Appliance (VCSA). I explained how to use vimtop in real time and capture vimtop data, and how to examine this data by using scripts, spreadsheets, or Perfmon to spot long-term trends that may adversely affect the performance of your VCSA. I presented examples of ways in which I used vimtop to spot real-time resource issues, and specifically how I used stored vimtop data to spot issues that would have otherwise crippled my VCSA's performance. I based the content of the session on articles I've written for Virtualization & Cloud Review; those articles can be located here. If you missed the U.S. session, I'll be presenting it again at VMworld Europe in Barcelona in early November.
After the session, I was approached with many questions about the VAMI and vimtop, so I wanted to highlight and share some of those questions and the answers I gave. Many thanks to all who asked questions during and after the session.
Do you need to enable BASH in the VAMI to run vimtop?
No -- and although not necessary, it's still useful to have the BASH tool set if you're going to export data from the VCSA.
Can I kill a process from vimtop?
No (and I think that this is a good thing). While you can use the job control in BASH to kill jobs, be very, very careful about killing a process. You can get the process identifier (PID) for the process that you want to kill from vimtop.
Can I only display specific processes in vimtop?
No. You don't have control over what processes are displayed in vimtop.
Can I only display specific counters (statistics) in vimtop?
Yes. Use a configuration file to specify the counters that you want to display.
Can you change the colors in vimtop?
Kind of -- you can change from color mode to black and white by pressing the tilde "~" character. I haven't found a way to specify a color scheme. I haven't seen this documented anywhere, so there's a possibility that this function may change, or this ability may be removed in the future.
Why not use vSphere performance monitoring tools to monitor the VCSA?
The vSphere performance monitoring tool only shows what the VM is doing, not what the processes within the VM are doing; vimtop can give you this insight. The vSphere monitoring tool can give Postgres database utilization.
Why should I use the tools that you showed in your session rather than a third-party tool?
I'm sure others have the same question about why using vimtop and the VAMI monitoring tool is more beneficial than other tools. A few reasons come to mind: VAMI and vimtop are free, come pre-installed, and a tool like vimtop can give you unique insight to the processes that are running on your VCSA. I'm not aware of any other monitoring agents that are certified to run on the VCSA.
What are the load averages on vimtop?
There are three load averages. They are one, five and 15 minutes. High load averages imply that a system is overloaded and that many processes are waiting for CPU time. They're from /proc/loadavg.
How exactly is the load average field calculated?
They use the same counter as a Linux system: /proc/loadavg. The load average field is calculated using a complex heuristics algorithm that incorporates many different sets of data inputs. To be honest, the usefulness of loadavg is a religious war; while some claim that it's a valuable counter, others say it isn't. I recommend monitoring it and seeing if it mirrors what you see in your system performance and then decide for yourself.
Again, thank you all for coming to my VMworld session and I hope these questions and answers help you.
Tom Fenton has a wealth of hands-on IT experience gained over the past 25 years in a variety of technologies, with the past 15 years focusing on virtualization and storage. He previously worked at VMware as a Senior Course Developer, Solutions Engineer, and in the Competitive Marketing group. He has also worked as a Senior Validation Engineer with The Taneja Group, where he headed the Validation Service Lab and was instrumental in starting up its vSphere Virtual Volumes practice. He's on Twitter @vDoppler.