Cloud Storage & Networking Basics
Understand object, block and file storage, and how virtual networks, subnets and security groups isolate and connect your cloud resources.
Three Types of Cloud Storage
Cloud providers offer storage in three shapes. Choosing the right one affects cost, speed and how your application accesses data:
- Object storage (S3, Azure Blob, Cloud Storage) — Flat namespace of files with metadata. Ideal for images, backups and static websites. Virtually unlimited and very durable.
- Block storage (EBS, Persistent Disk) — Raw volumes attached to a single virtual machine. Used for operating systems and databases.
- File storage (EFS, Azure Files) — A shared network file system many machines can mount at once.
Virtual Private Cloud (VPC)
A VPC is your own isolated virtual network inside the provider's data centers. You choose the IP range and divide it into subnets:
Public subnets have a route to an internet gateway, so resources can be reached from the internet. Private subnets have no direct internet route and are used for databases and internal services.
Security Groups and Firewalls
A security group is a stateful firewall attached to a resource. Follow the principle of least privilege: only open the ports a service actually needs, and restrict sources wherever possible.
import boto3
ec2 = boto3.client("ec2", region_name="us-east-1")
# Create a security group in an existing VPC
sg = ec2.create_security_group(
GroupName="web-sg",
Description="Allow HTTPS from anywhere",
VpcId="vpc-0abc1234def567890",
)
ec2.authorize_security_group_ingress(
GroupId=sg["GroupId"],
IpPermissions=[
{
"IpProtocol": "tcp",
"FromPort": 443,
"ToPort": 443,
"IpRanges": [{"CidrIp": "0.0.0.0/0"}],
}
],
)
print("Created", sg["GroupId"])Load Balancers and DNS
A load balancer spreads incoming traffic across multiple healthy instances, providing both scale and availability. DNS services (Route 53, Cloud DNS) translate friendly names like `app.example.com` into the load balancer's address and can route users to the nearest region.
Key Takeaways
- Use object storage for files, block storage for disks and file storage for shared access.
- A VPC isolates your network; private subnets keep databases off the public internet.
- Security groups should open only the ports a service needs.
- Load balancers and DNS provide scale, availability and friendly names.
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