The "Cloud" Isn't Up in the Sky
"Save your photos to the cloud," "work in the cloud" - we use the word "cloud" every day. Represented by a fluffy cloud icon, some people might imagine their data floating somewhere up in the sky.
In reality, however, the cloud is simply "computers in massive data centers located around the world." In the IT industry, there's a famous joke: "There is no cloud. It's just someone else's computer."
The Reality of Data Centers
Your iPhone photos, Gmail emails, Netflix movies - all of these are stored on servers inside enormous buildings somewhere in the world.
- Google: Operates data centers in over 30 locations worldwide. Each data center houses hundreds of thousands of servers
- Amazon (AWS): Deploys data center clusters across more than 30 regions worldwide
- Microsoft (Azure): Operates in over 60 regions
Data centers are buildings the size of several soccer fields, with tens of thousands of servers neatly arranged in racks. They operate 24/7/365 and require massive amounts of electricity and cooling equipment.
Why Is It Called the "Cloud"?
Since the 1990s, there has been a convention of representing the internet as a "cloud" shape in network diagrams. Internal networks are drawn in detail, but the internet's internals are too complex, so they're abstracted as a cloud. "Computers on the other side of the cloud" became "cloud computing."
In other words, "cloud" is more of a marketing term than a technical one - a friendly way to express "computing resources accessible via the internet."
Where Is Your Cloud Data Actually Stored?
"Which country is my data in?" - This is a surprisingly important question.
- iCloud (Apple): Data from Japanese users is primarily stored in data centers in the United States and China (China mainland users only)
- Google Drive: Data is distributed across multiple data centers. Users don't know which country it's in
- AWS: You can choose a region, so selecting "Tokyo Region" stores your data in data centers within Japan
The EU's GDPR applies strict rules when transferring EU citizens' data outside the EU. The physical location of data carries significant legal implications. Regardless of where your cloud data resides, enabling device encryption on your local devices ensures that your data remains protected even if the device is lost or stolen.
What Happens When the Cloud "Goes Down"
When a cloud service experiences an outage, the impact is widespread. During AWS's S3 outage (2017), numerous services including Netflix, Slack, and Trello went down simultaneously.
There's an image that "the cloud is safe," but ultimately it's physical computers. Power outages, cooling system failures, software bugs, human error - the causes of outages are no different from your own PC. The difference is that when an outage occurs, the number of affected users is orders of magnitude larger.
Summary
The cloud isn't up in the sky - it's physical computers in data centers around the world. We recommend keeping the awareness that you're entrusting your data to "someone else's computer" and maintaining local backups of important data. For practical steps on protecting your files in the cloud, see our guide on cloud storage security. When you access IP Check-san, that request is also being processed by a server in the cloud.