Although I am a product of architect, and my colleagues criticized me for doing nothing more than boxes and drawing lines all day, I receive from time to time to roll up my sleeves. I recently worked on a project that was to collect detailed information on the storage I / O performed by a "typical" office running in a virtual machine for a day in the office. I captured a record of all I / O caused by the VM, then put in the data analysis in the evening. That's when I noticed something a little strange that re-enforced the need for storage optimization your image VDI operating system.
hope my boss is not reading this, then it will not realize that I only got a couple hours of work done before I headed for lunch, but here are the charts that m ' did do a double-take:
in case you're wondering, these charts show the same data, but taken in two ways. The top graph is a perfmon capture storage operations per second of my VM, the more it is the same data calculated from the raw track of all the I / O of the virtual machine and displayed in Excel. They present the same reasons, which gives me confidence that we see something real. In addition, the two graphs are reduced by a factor of 10, so I can fit them together for comparison - the peak IOPS was over 100.
Check out this great period of high activity disc from about 24:30? It is true then I headed for lunch. And look, it stops just as suddenly when I returned to my office. Huh -. Who is "weird", almost like my office was more work when I was not there
So how much I / O represent this period? Here is a graph showing the I / O for the VM cumulative over time:
This is a huge proportion of the global I / O activity for the whole day which took place in a short period where I'm not even use my office. Of the 541,369 I / O operations for the day, more than half were generated while I was enjoying my lunch.
I am curious by nature, decided to take a look at the nature of the I / O write is executed. Ruben Spruijt showed that generally 4KB I / O dominant OS for desktop computers, and this is what we normally see as well - but look at the data I captured:
Overlooking the whole day, 16KB I / O operations accounted for over 60% of all read operations for the office. This disparity was caused by this mysterious mid-day activity? I suppose: (in blue)
Thus all round ways, this amount is severe load storage - what happens
After have dug around? I find that the operating system image had a number of scheduled tasks that are configured with their default out-of-box to run on every boot after 10 minutes of inactivity. Looking at these tasks, they all started precisely 24:38:
- Autochk
- Diagnosis
- SystemRestore
I can t be course of these was the culprit, but we have our smoking gun.
Optimizing OS
In a VDI deployment is highly recommended that you optimize the operating system for efficient storage utilization. This is a technology that has been a key component of Citrix Provisioning Server for many years:
Many people do not realize that for XenDesktop 5, this tool is now such an integral part of XenDesktop silently we run this tool as part of the Citrix installation code that runs in user workstations -. if you use MCS, PVS or arrangement will work stations using your own scripts you get the benefit
You should not have to remember to do it
When we designed XenDesktop 5, we decided that storage optimization is essential that we would not be offered the opportunity to not optimize the behavior of the operating system.
Some of these optimizations are not things you want done silently and automatically, so we do not execute -. such as disabling the password change computer account or disabling the basket
why I see so great I / O bump in my footsteps? I had not installed Citrix Desktop Software -. For the purpose of my project, I wanted a vanilla environment
The optimization tool is automatically run only if you install the desktop software using the wizard 'autorun' (autoselect.exe) - if you install the individual MSIs, you will not benefit from this automatic optimization. The tool is installed (but not run) by the MachineIdentityServiceAgent_ {x86 | x64} .msi file, and can be run directly from C: Program Files Citrix PvsVm TargetOSOptimizer TargetOSOptimizer.exe
Conclusions
I think there is a certain number of things we can all learn from my experience.
First, as an industry, we must allow periods "inactive" in our validation VDI deployment and load testing tools. Many large-scale testing examines the system under load - but as the data above shows, if a computer is not fully optimized, Windows has a habit of storing up problems when least expect
Second ,. always, always optimize your operating system for storage performance - either by having XenDesktop automatically by executing an optimization tool yourself if you opt for a more advanced type of installation -. or even perform optimizations "by hand" on a master image
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