High-performance block storage for VM instances with automatic replication, snapshots, and flexible performance scaling.
What is Google Cloud Persistent Disk?
Persistent Disk is the primary block storage service for Google Compute Engine VMs. The service provides persistent, network-based storage that exists independently of the VM lifecycle. Data persists when VMs are stopped or deleted, and disks can be moved between VMs or attached to multiple VMs in read-only mode. This flexibility makes Persistent Disk the standard storage for databases, application data, and boot disks.
A core feature is automatic replication within a zone, protecting data from hardware failures. Regional Persistent Disks even replicate across two zones for higher availability. Incremental snapshots enable efficient backups that are globally available and can be restored in any region for disaster recovery. The snapshot technology only stores changed blocks, reducing costs and minimizing backup times.
Persistent Disk offers four performance tiers: Standard HDD for cost-effective sequential workloads, Balanced SSD for general production workloads, Performance SSD for I/O-intensive applications, and Extreme SSD with up to 100,000+ IOPS for specialized high-performance requirements. Disk size can be up to 64 TB, and performance scales largely with size. Encryption-at-rest is enabled by default, with optional customer-managed encryption for additional control.
Common Use Cases
VM Boot Disks for Compute Engine
Persistent Disk serves as standard boot storage for all Compute Engine VMs. Boot disks contain the operating system and can be snapshot-cloned for rapid VM cloning. Balanced SSD offers the best price-performance ratio for boot disks, while Standard HDD suffices for development and test environments.
Database Storage for MySQL, PostgreSQL, MongoDB
Persistent Disk is ideal for relational and NoSQL databases. Balanced SSD provides sufficient performance for medium-sized databases (up to 10,000 IOPS), while Performance or Extreme SSD is needed for large OLTP workloads with high transaction rates. Regional Persistent Disks provide additional availability for critical databases.
Persistent Storage for Container Workloads
Google Kubernetes Engine (GKE) uses Persistent Disk for PersistentVolumes. Stateful sets like databases or message queues can dynamically provision Persistent Disks via Kubernetes volume claims. This combines Kubernetes flexibility with Persistent Disk reliability.
Snapshot-based Backups and Disaster Recovery
Incremental snapshots enable efficient backup strategies. Automated snapshot schedules back up data regularly, while global snapshot availability enables cross-region disaster recovery. Example: A company creates daily snapshots and retains them for 30 days for compliance requirements.
Log Aggregation and Analytics Workloads
Standard HDD is suitable for log aggregation and data lake storage, where high throughput is more important than IOPS. Combined with Cloud Storage for long-term archiving, Persistent Disk provides cost-effective intermediate storage for analytics pipelines.
Best Practices
Choose the Right Disk Type
Balanced SSD is the default choice for 90% of production workloads. Use Standard HDD only for archives or sequential reads. Performance SSD is worthwhile from 30,000 IOPS, Extreme SSD only for specialized requirements over 80,000 IOPS. Test performance before switching to more expensive tiers.
Use Snapshot Schedules
Automate backups with snapshot schedules instead of manual snapshots. Define retention policies (e.g., daily for 7 days, weekly for 4 weeks, monthly for 1 year). Snapshots are incremental and cost-effective, even with frequent creation.
Regional Persistent Disks for Critical Workloads
Use Regional Persistent Disks for databases and other critical services requiring high availability. Replication across two zones protects against zonal failures. Note higher latency (a few milliseconds) due to cross-zone replication.
Monitor IOPS and Throughput
Use Cloud Monitoring for disk metrics like read/write IOPS, throughput, and queue depth. High queue depth indicates I/O bottlenecks. Switch to a higher tier or increase disk size for more performance.
Encrypt Sensitive Data
Use Customer-Managed Encryption Keys (CMEK) for sensitive data to have full control over encryption keys. This meets compliance requirements and enables key rotation. Standard encryption-at-rest is always enabled.
Google Cloud Persistent Disk Comparison
vs. AWS EBS: Persistent Disk offers simpler pricing models without distinguishing between IOPS-provisioned and throughput-optimized. EBS has more tier options (gp3, io2, st1, sc1), while Persistent Disk has four clear tiers. Both offer similar availability and snapshot features.
vs. Azure Managed Disks: Azure distinguishes between Standard HDD, Standard SSD, Premium SSD, and Ultra Disk, similar to Persistent Disk. Azure offers disk bursting for temporary performance spikes, while Persistent Disk delivers consistent performance. Pricing models are comparable.
vs. STACKIT Block Storage: STACKIT offers data sovereignty in German data centers, while Persistent Disk has global reach with EU regions. STACKIT is suitable for compliance-critical workloads, Persistent Disk for global scaling.
Integration with innFactory
As a Google Cloud partner, innFactory supports you in selecting the right Persistent Disk tier, migrating from on-premises storage to GCP, and optimizing storage costs. We help with snapshot strategies, performance tuning, and integration with Kubernetes and Compute Engine.
Contact us for consulting on Google Cloud Persistent Disk and storage architectures.
Available Tiers & Options
Standard (HDD)
- Cost-effective
- Good for sequential workloads
- Up to 64 TB per disk
- Lower IOPS and throughput
- Not for latency-sensitive applications
Balanced (SSD)
- Balanced price-performance ratio
- Good performance for databases
- Higher IOPS than Standard
- More expensive than Standard HDD
- Lower performance than Extreme SSD
Performance (SSD)
- High IOPS and throughput
- Low latency
- Ideal for databases and analytics
- Higher costs
- Overkill for simple workloads
Extreme (SSD)
- Highest performance
- Customizable IOPS
- Sub-millisecond latency
- Most expensive option
- Only for specialized high-performance workloads
Typical Use Cases
Technical Specifications
Frequently Asked Questions
What is Google Cloud Persistent Disk?
Persistent Disk is a highly available block storage service for Google Compute Engine VMs. The service offers automatic replication within a zone, incremental snapshots for backups, and various performance tiers from Standard HDD to Extreme SSD.
Which disk type should I choose?
Standard HDD is suitable for sequential workloads and archives. Balanced SSD offers the best price-performance ratio for databases and applications. Performance SSD is ideal for I/O-intensive workloads. Extreme SSD should only be used for specialized high-performance requirements with over 80,000 IOPS.
How do snapshots work with Persistent Disk?
Snapshots are incremental backups that only store changed blocks since the last snapshot. The first snapshot is a full copy, subsequent snapshots contain only deltas. Snapshots are globally available and can be restored in any region for disaster recovery.
Can I move Persistent Disks between VMs?
Yes, Persistent Disks can be detached from one VM and attached to another VM. In read-only mode, disks can even be attached to multiple VMs simultaneously. This enables flexible workload migration and shared storage scenarios.
How is Persistent Disk billed?
Persistent Disk is billed based on provisioned storage per GB/month, regardless of actual usage. Additional costs apply for snapshots and I/O operations for Extreme SSDs. Balanced SSD offers the best price-performance ratio for most workloads.
What is the difference between Persistent Disk and Local SSD?
Persistent Disk is network-based, persistent, and survives VM restarts. Local SSD is physically attached to the host, offers higher performance, but data is lost when VMs stop. Persistent Disk is suitable for databases and critical data, Local SSD for temporary caches and scratch space.
How high is the reliability of Persistent Disk?
Persistent Disk automatically replicates data within a zone across multiple physical disks. Regional Persistent Disks replicate across two zones for higher availability. Combined with snapshots, this provides robust disaster recovery options.
Can I change the performance of a disk afterwards?
Yes, you can change disk types and increase size without stopping the VM (for most OS). Switching from Standard to SSD or from Balanced to Performance SSD is possible without downtime. Reductions are not supported.
Is Persistent Disk GDPR compliant?
Yes, Persistent Disk is available in EU regions and meets all GDPR requirements. Google Cloud offers comprehensive data protection controls, compliance certifications, and data residency options for European customers.
