Virtualization's forgotten feature: Short reboot times
In many ways, virtual machines are a system administrators dream come true. Short boot times, though an often forgotten feature, are part of that dream. If you haven't thought about it, how much time do you spend per year rebooting and waiting on systems? Trust me, it's more than you realize. Virtual machines alleviate the long waits, the potential hardware failures, and the endless questions for status updates. Virtual machines still need rebooting, but without the waiting. So if you think you spend half your life waiting on systems to reboot, you're not far from the truth.
Reboot a physical system and wait. And wait, and wait, while the other callers on the maintenance call sound like young children on a long road trip, "Are we there yet?"
Here's a very typical dialog that many of you are familiar with from your own experience:
12.18am: Can you go ahead and reboot that system?
Sure, rebooting now.
12.20am: OK, where are we with that system?
It's still shutting down. Some services take a while to close.
12.23am: Can you give us a status on that system?
It's just now going through POST.
12.26am: What's our status?
You reply calmly: It's coming up. Right now, it's still checking hardware.
12.30am: Is it up yet?
No, Windows is starting.
12.33am: Is there a problem with the system?
No, it's almost at a logon prompt.
12.36am: Are we there yet?
Yes, I'm logging on now.
Sound vaguely familiar to you? It should if you're in the business of rebooting systems for maintenance or troubleshooting. Just for fun, here's that same conversation with a virtual machine as the topic:
12.18am: Can you go ahead and reboot that system?
Sure, rebooting now.
12.20am: OK, where are we with that system?
It's still shutting down. Some services take a while to close.
12.23am: Can you give us a status on that system?
12.26am: Are we there yet?
Yes, I'm logging on now.
Many virtual machines don't have any trouble shutting down or booting up, and boot times can take less than four minutes. Those of you who have experience with both types of systems know that I'm not exaggerating. If I've exaggerated in this demo, it's in shortening the time for a physical system reboot, and lengthening the amount for a virtual system reboot. The illustration is simply a demonstration of the difference between the two.
Reboot times are no longer a significant time problem during maintenance windows, which lowers the duration of maintenance windows considerably. It also makes troubleshooting through multiple reboots a lot less tedious. If you have to employ a team of system administrators to manage hundreds of server systems who reboot servers at least once a month for patching, you've saved a huge amount of time — time that translates as less down time.
Time is money.
You're not just saving your system administrator's time. Add up the time saved for everyone on that call, plus time saved for the hardware guy standing by in the datacenter in case of a hardware failure.
You can do the math yourself. The savings is huge.
Converting your physical systems can save money, you know that already. It can save labor too. But most of all, it can save time.