A virtual machine is disposable. Your data should never be.
So when a VM runs in Google Cloud, where does its data actually live—and why doesn’t it vanish when the VM does?
The answer in Google Cloud Platform (GCP) is Persistent Disk.
So, What Is Persistent Disk?
Persistent Disk (PD) is Google Cloud’s block storage service designed specifically for Compute Engine virtual machines. In simple terms, it functions as the virtual hard drive for your VM. Unlike local disks, Persistent Disks are durable, scalable, and independent of the VM lifecycle.
Key Features of GCP Persistent Disks
- Data Persistence
One of the most important advantages of Persistent Disk is right in its name—persistence. Data remains intact even if the VM crashes, stops, or is deleted. - VM Independence
Persistent Disks are independent resources. You can detach a disk from one VM and attach it to another. - Flexible Attachment
A Persistent Disk supports one read-write attachment and multiple read-only attachments. - Reliable Storage
Built with automatic replication to protect against hardware failure.
Each Persistent Disk supports:
- One read-write attachment
- Multiple read-only attachments
This makes it suitable for both standalone workloads and shared read-heavy architectures.
Types of Persistent Disks in Google Cloud
Google Cloud offers multiple Persistent Disk options to match different workload needs.
Standard Persistent Disk (pd-standard – HDD)
Best for:
Cost-sensitive workloads like backups, batch jobs, and archival storage.
Performance:
Moderate performance using traditional hard disk drives (HDDs).
Balanced Persistent Disk (pd-balanced)
Best for:
General-purpose workloads such as application servers and development environments.
Performance:
A balance between price and performance, offering higher IOPS than standard disks.
SSD Persistent Disk (pd-ssd)
Best for:
Databases, analytics engines, and transactional systems.
Performance:
Low latency and high IOPS using solid-state drives (SSDs).
Extreme Persistent Disk (pd-extreme)
Best for:
Mission-critical workloads that demand consistently high performance.
Performance:
Ultra-low latency with predictable, high IOPS—ideal for large enterprise databases.
Key Takeaway
Persistent Disks are the foundation of storage for Google Compute Engine VMs.
They provide durable, flexible, and high-performance block storage while keeping your data safe beyond the lifecycle of a virtual machine.
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