Which would your CEO prefer

Would your CEO choose to give up a negligible amount of system performance at peak system load in exchange for a reduction of risk during system upgrades and an alternative to hours of downtime?

I suspect the answer is yes.

What’s the cost of such a technology? Believe it or not, it’s free. It’s the snapshot functionality that’s built into VMware’s vSphere Hypervisor (based on ESXi) that you can leverage once you virtualize your Oracle database or any other x86 systems. Is the performance impact truly negligible? Don’t take it from me; you can read it in Oracle’s own words.

Recently RedHat and Oracle have come out with updates to their mainstream distributions (RedHat Enterprise Linux 5.6 and Oracle Linux 5.6) and each has come out with an entirely new version (RedHat Enterprise Linux 6 and Oracle Linux 6). System and database administrators all around the world are updating their critical systems. Applying those updates to critical systems requires testing and downtime.

The best practice for operating system upgrades is to test the upgrade on the same exact hardware, software and data as in production. But are your test and production systems identical? Same motherboard? Same processors? Same amount and brand of RAM and same exact operating system packages installed? Pretty unlikely. With virtualization, all those configurations are identical.

With VMware virtualization, I can take take a clone of the entire production server while it’s live and being used by users. Now I have a truly identical copy of production to test my upgrade. Note that to do a clone of the entire production server while it’s live requires VMware vCenter which isn’t free, but vSphere Essentials (which includes vCenter) starts at $1000 as of the time of this writing.

With snapshots (which are free and don’t require vCenter), you take a snapshot (3 mouse clicks and less than 10 seconds) of the virtual machine and then do the upgrade. If you run into issues, just revert / rollback the snapshot to the state it was in when you took the snapshot. The time to do that revert / rollback is only the time necessary to reboot your virtual machine – 5 minutes? If the upgrade and testing goes smoothly, you just merge the snapshot into the virtual machine while the system is up and available to users. Total time spent doing non-upgrade activities such as backups or restores? Essentially zero.

Compare this to how you would handle a critical system without virtualization: you’d take the system offline for the upgrade, take a full backup of the system, do the upgrade (hoping it works just like it did in the similar but most likely not identical test system), have the users test, and, if there’s an issue, possibly spend hours restoring from backup. You do trust your backups… right?

Enterprise DBAs and the companies that employ them tend to be risk adverse when it comes to losing data or experiencing downtime. Virtualizing the hardware allows you to ensure your test and development systems are the exact same systems as production, thereby reducing risk of unforeseen issues during the upgrade. Utilizing snapshots allows you to very quickly take a save point of your entire server and rollback to it very quickly in the event of unforeseen issue, almost entirely eliminating (minutes vs. hours) the downtime associated with recovering from an unforeseen issue.

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