Ever since ESX 2.5 I have always been looking for cool free tools to monitor my hosts. I guess one of the oldest free tools out there is vmktree. Especially in the 2.x timeframe vmktree helped me out solving some weird performance issues. Back then vmktree was still dependent on vmkusage (who remembers that one?) but as of ESX 3.0 vmktree utilizes the api to gather the details needed to plot the graphs.
I lost track of vmktree for a while but when I noticed the announcement this week that 0.4.1 was released I decided to give it a spin again. I logged into my vSphere Management Appliance (vMA) and downloaded vmktree with wget. Installed it following the procedures mentioned in the announcement and literally minutes later I could see the first values coming in. To make sure I had something to show you guys I added a limit of 200MB on a virtual machine. As you know I love esxtop but esxtop are still just “dry numbers” which makes it difficult to see a trend. As you can see in the following screenshot, vmktree makes this trend pretty obvious. (Balloon driver is really active and the size of the balloon is increasing._
Besides memory, of course vmktree has more to offer on both per VM and Host level. For instance on a per VM level you can also see CPU and Storage statistics. On a Host level you can see CPU, Storage and Network. Of course these would include things like Latency, Bus resets, dropped packets, disk space usage… you name it, it is in there.
I know there are a lot of vendors these days offering free monitoring solutions, but the cool thing about vmktree is that it is maintained by just a single person Lars Troen. I can only imagine how much work maintaining a tool like this is. Thanks Lars for helping me out by writing this excellent tool! I would like to ask everyone to give it a try, and of course to provide feedback to Lars so that he can possibly improve vmktree over time.