Reasons for Operating System Retirement
This article applies to: Managed Servers
An operating system is typically supported by the vendor for a few years after the last ship date, but eventually new patches are not produced and vendor support is significantly reduced. At that point, the Systems Support group can no longer effectively manage the operating system and will request a retirement date for any server on which it is installed.
In most cases, the 4-5 year hardware replacement cycle will necessitate moving to newer operating system versions so that older versions naturally phase out. Both hardware replacement and operating system version will be discussed during the annual maintenance meeting with customers.
The current list of supported operating system versions is on the Supported Operating Systems and Hardware page.
Below are some links from the vendor used to gauge timing. Solaris machines are targeted for retirement near the end of Phase 1 retirement, Windows machines near the end of Mainstream support.