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Overview

Polystack Block Storage delivers persistent block volumes to compute instances through a distributed service architecture. The service separates its API layer, scheduling logic, and backend drivers — enabling flexible backend configurations, horizontal scaling, and multi-backend deployments where different hardware tiers serve distinct workload categories.
Administrator Access Required — This operation requires the admin role. Contact your Polystack administrator if you do not have sufficient permissions.

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Architecture Diagram

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Principal Components

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Request Flow

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Volume Create

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Volume Attach

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Backend Driver Model

The backend driver is the component that communicates with the physical or virtual storage system. Polystack Block Storage supports multiple drivers that can be active simultaneously:
Production deployments should use the distributed storage (RBD) driver. LVM is acceptable for single-node development environments and should not be used where data durability is required.

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Multi-Backend Deployment

Polystack Block Storage supports multiple concurrent backends. The scheduler filters backends using configurable filters and selects the optimal backend using a weighting algorithm: The CapacityWeigher (default) prioritizes backends with more free capacity to spread load across the cluster.

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High Availability

In a high-availability deployment:
  • The Block Storage API runs on all control plane nodes, load-balanced via the VIP
  • The Scheduler runs on all control plane nodes (active-active)
  • The Volume Service runs on each storage node (active-active per backend)
  • The Database uses Galera multi-master replication across control plane nodes
  • The Backup Service runs on one or more dedicated nodes
the deployment console automatically configures high-availability service placement based on your cluster topology. Manual service placement is not required for standard deployments.

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Next Steps

Storage Backends

Configure distributed storage, LVM, and NFS backend drivers

Volume Types & QoS

Create volume types and enforce I/O quality-of-service limits

Storage Tiers

Configure NVMe, SSD, and HDD tier mappings for multi-tier deployments

Admin Guide

Return to the Block Storage administration overview