Data centers replace web servers without losing customer data by first moving the data from the old server to the new server first, before decommissioning the old server.
Data centers use redundancy, live migration and even real time synchronization to ensure data is maintained and moved to the new server when it's replaced without losing the customer data.
The data center tech ensures that service continues through high availability infrastructure Tier III/IV, where the new and updated web servers are first brought online to take over the traffic of the old server before the old server is turned off and decommissioned, which creates zero downtime for user data.
Data centers will maintain extra redundant servers and storage, often with 2N configuration, which means that they have 2 independent, fully operational systems.
And if one should fail or is being replaced, the other server handles the entire workload.
Live migration of customer data when replacing web servers is also done through virtualization, using virtualization tools, virtual machines are moved from a physical server that is slated for replacement to a new one while they are running with no disconnection for the end user.
And the data is often rarely stored exclusively on the web server itself as it's also stored sometimes in central, highly available SANs that multiple web servers can access simultaneously and when a server is replaced, the new server will simply connect to the same data source.
Also before disconnecting an old server, traffic is first redirected through a load balance to a standby server and the original server is then only decommissioned and turned off and disconnected once it's workload is fully verified as successfully transferred and operational on the new hardware.
Web server hard drives last between 3 years to 5 years as they are in active, 24/7 service.
Some web server hard drives can also last over 6 years, and they can even function longer.
But as the hard drive ages, the risk of the hard drive failing increases greatly after 4 years, which makes 3 to 5 years a standard timeline for replacement of the server hard drives for ensuring data reliability and preventing data loss.
The constant, heavy read/write operations, which are typical in web servers increases the wear on the hard drives and high heat, humidity, and excessive vibrations can also reduce the hard drive's life significantly.
And enterprise grade server hard are also designed for higher durability and 24/7 operation, when compared to hard drives for desktops.
Also because the HDDs in the servers have spinning platters, and moving parts, they eventually will wear out and failure rates of the servers hard drives often follow what's known as a bathtub curve that is higher in the first few months and after 3 years to 5 years.
Solid state server hard drives are also commonly used in web servers and often have a 3 year to 5 year lifespan, which is usually governed by their endurance rating, which is how much data can be written to them over time.
The hard drives usually show signs of failure before they do fail and the data center techs can replace them before they actually fail.
In Raid Array hard drives the data is copied on more than one hard drive and so when one hard drive starts to fail, the hard drive can be pulled out and a new one pushed back into place and the data will then be copied back to the new hard drive without any downtime or data loss.
Data centers replace web servers as often as every 3 years to every 5 years.
3 years is a common time frame for when data centers traditionally refresh and replace their web servers, which is often driven by warranty expiration's.
Although many data centers also extend the time to 5 or even 6 years before replacing the actual web server as a result of improved reliability of hardware and budget considerations.
Data centers also replace hardware most often before they replace the actual server.
For example hard drives in servers may be replaced within 4 to 5 years or sometimes sooner if they are starting to fail.
Data center servers often use hard drives like Raid Array, which copies data from one hard drive to another and more.
So when the hard drive is starting to fail, the data is copied to other hard drives on the server to prevent data loss and downtime.
Then when the old hard drive is pulled out and a new one is put back in it's place, the data is then copied back onto the new hard drive.
The hard drives in servers often have a light on them that also lets the data center tech know if they are about to fail and they are replaced before they actually do fail.
Research also indicates that server performance in data centers can also drop by 14 percent annually and lead to a 60 percent drop by 5 years.
And older web servers cost the data center more to maintain and use more power relative to the performance of newer server models.
And major data center providers like Google, Microsoft, Amazon etc also have pushed server lifespans to 5 to 6 years to save costs and reduce the amount of e-waste.
And while data center servers can often last as long as 8 years, if they are well maintained, the components of the data center servers like hard drives, usually fail around 5 years.
Other components in data centers like networking gear often last 3 years to 5 years, cooling units last around 12 years and the building itself can last for a very long time.
The wires, and other components can also last 15 years or even longer.