Server OS upgrades are part of the everyday life of the IT admin and the never-ending cycle brings plenty of challenges....
Different hardware platforms application needs and virtualization options have greatly affected how we approach this upgrade puzzle. With so many different options, you must examine the positives and negatives before upgrading or replacing.
Many administrators use the application upgrade process as a chance to update the OS, move to new hardware or even make the leap to a virtualization platform. However, there are several factors that can weigh heavily on that decision, so let's look at a few options.
With each new release of Windows, Microsoft has gone to greater lengths to ease the Windows Server upgrade process. The general procedure has been pain free for most upgrades as long as you are upgrading directly from a previous OS. However, if you skip versions, such as upgrading from Windows server 2003 to Windows server 2012 (skipping Windows 2008) you may encounter additional challenges. While skipping an OS can cause problems, updating the application often presents a larger challenge.
Updating applications before upgrading Windows server
In a scenario with a legacy application running on an old OS, you may need to first upgrade the application before you can install a new OS. However, the out-of-date application may not function on a newer OS and administrators can face a catch-22 scenario. In this situation, the administrator must usually wait to upgrade until it is necessary. When that point comes, it is truly a choice of which upgrade will cause the least amount of damage. When you are stuck between a rock and a hard place, it's best to look for the softest rock you can find. In this case, that would be the Windows Server upgrade.
In many cases, you will be unable to update the application before upgrading the OS, even if the OS upgrade will break the application. Luckily, many applications do not need to be working to be upgraded. Of course, there is no guarantee of success, but this is usually the best option when faced with a difficult situation.
Virtualization has brought a lot of flexibility when it comes to server upgrades. One of the biggest impacts has been the ability to do a physical to virtual migration. Taking a physical server and migrating it to a virtual instance within just a few hours has helped to fuel the growth of the virtual infrastructure. While this is more of a migration than an upgrade, it has helped to propagate the practice of migrating versus installing the application on a new VM. This approach saved time, but it also burdened servers with legacy data that could affect performance, increase backup size and introduce security risks.
Using virtualization management tools
While installing new would enable the admin to have a clean and secure OS, often times the concept of upgrading and moving to a virtualized platform was simply too much change for management and application owners. In these cases, IT was forced to ease in the changes with two steps. IT admins would first migrate the server to a VM, and then focus on upgrading the OS later. However, we now have the virtualization management tools to help.
In an ideal environment, we would create a brand new server and reinstall the application. Unfortunately, application media gets lost, or the person originally responsible for the application has moved on. The good news is with virtualization is cloning and snapshots will become your best friend for this.
Cloning your target machine is ideal for a quick test platform without an interruption of service. You can take a clone at almost any time and disconnect the clone from the network. With this clone, you have the ideal upgrade test platform. Having the ability to perform the upgrade without the pressure of getting it back online is well worth the time and additional storage space of a clone. Once you have learned everything you need to know, including the amount of downtime the upgrade will require, you can schedule the real server for the upgrade with a known outage window. Your additional safety net during the upgrade is the snapshot, which gives you the ability to snap back to a point before the upgrade in the event something goes horribly wrong. The important thing to remember about snapshots is to ensure they are removed after the upgrade has been completed.
Upgrading an OS can be a challenge, but virtualization can help us ease the pain. The Windows Server upgrade process is an opportunity to make positive changes that you might not normally be able to address.
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