Before upgrading your operating system, whether it be a Windows system, OS X, Linux or other Unix derivative, it is always advisable to back you data up first. Often however, this only happens the very first time you do an upgrade, if at all, especially if nothing untoward happens the first time.
It is easy to become complacent, because the chances of a problem occurring which leads to loss of data is low. However, when a problem happens, the only course of action is to send the hard disk for data recovery.
Preparing For OS Upgrade
The preparation for an upgrade is important, especially if the operating system is update being installed over an existing version. It is this situation when problems are most likely to happen, such as incompatibility problems or unexpected file system corruption. With user areas often located by default on the same partition as the operating system, important data could be rendered inaccessible.
If the operating system is being installed to a new partition, or overwriting an existing one, it is important to double check that correct disk and partition have been selected. A simple mistake, especially when deciding to overwrite an existing partition which is being reformatted, is easy to make. It could lead to data being lost, which could be completely unrecoverable.
Operating System Downgrade
The desire to downgrade back to previous operating occurs many times, whether the user dislikes the newer version of the operating, it has compatibility issues, or the operating runs slow on the hardware. Although downgrading is technically possible, in many cases the complications, particularly if the operating system has been running for a while, can be insurmountable.
Should you decide the new version of the operating system does not meet your needs, either due to the interface or it runs too slow, it is imperative that any data not already securely backed up is made safe. In order to downgrade the operating it may be necessary to reinstall the previous operating from scratch.
Data Recovery Following Upgrade Failure
It is important that if something does go wrong with your upgrade or downgrade that you do not panic, particularly if you have not previously backed up all your data. The worst possible case is reformatting a partition which contained data, onto which the new operating system was installed, as the chances of recovering the previous data reduces, the more applications you have installed.
Always be sure what you are doing before you start, as mistakes are very easy to make, as it is not always easy to know which drives contains what data when installing a new version of an operating system. All it takes is a momentary lapse of concentration to delete or reformat the wrong partition, which would require a complex data recovery, the results of which cannot be easily predicted without a full analysis.