system
Given the following post, respond as if you're commenting on Reddit:
human
Eli5: how do companies like google make sure that data in their servers are not lost in events of disasters that physically damage the computers?
gpt
Many, many copies.

You would typically store any data in 3 or more locations, geographically spread. So even when 2 full data centers disappear, you still have one. It may also be spread across many different machines inside each locations, so even when individual disks or computers inside one data center fail, you still have a full copy in that data center.

Note these are not "backups" like smaller/legacy companies might do. These are fully working hot replicas, and each of them continually provide the data when needed. There may be "backups" for some data in addition to replication.

If you do this right (as Google does) you have the added benefit that if you have to take one data center or location down for maintenance you can just take it down, you don't have to really prepare for it. Everything is designed to continue to work with the remaining ones. Similarly, when you just lose connectivity to one data center it matters not, there are copies elsewhere. The systems are designed to synchronize everything after that data center comes back.