Thursday, December 14, 2006

Live Upgrade

Solaris OS has a pretty cool technology if we want to upgrade our computer to some later release of the OS. It is called Live Upgrade. It basically works like this:
When you first install Solaris on your computer, you leave some disk space free for the future. It is not a problem since disks are cheap now. Only thing is to remember to set aside some space during first installation. When at some later time a new release of the operating system comes up and you want to install it without having to shut down your system, you can use Live Upgrade. It basically is really Live Upgrade. No downtime while upgrading. Now how many OSs have such cool stuff!
Ok so you are ready to upgrade. You just make a copy of your existing operating system boot image. It's just a command away and the empty disk space has the copy of existing Solaris. Another command and the copy gets upgraded to whatever newer release you have. Once the upgrade is over, simply set the newly upgraded space as the boot option and just one reboot after this you are running the latest bits of the OS. See? The downtime is just one reboot. All the time the system was upgrading you were using the system while the upgrade was going in the background. It just made your system a bit slower, that's all!
Though an individual can afford to waste a couple of hours in upgrading the system by shutting it down, data centers don't have such luxury. That's why they use Live Upgrade. The downtime when they want to use the latest OS is just one reboot time. It has an additional advantage. If for some reason the upgrade fails and you can't reboot into the newly upgraded partition, just revert back to the old working disk partition as your boot OS and it will work fine!

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