Azure Managed Diskshigh

• Azure Managed Disks are fully managed with automatic redundancy (3 replicas, 99.999% SLA); Cinder durability depends on backend.
• Predefined disk types (Ultra Disk, Premium SSD v2, Premium SSD, Standard SSD, Standard HDD) with fixed performance tiers; Cinder uses volume types with configurable QoS.
• Disks billed on provisioned size regardless of use; Cinder billing typically on provisioned size too but varies by provider.

Volumeshigh

• Uses proprietary /v2/volumes API instead of OpenStack Cinder /v3/{project_id}/volumes; actions like attach/detach/resize via undocumented POST /volumes/{id}/actions rather than /os-volume-attach etc.
• Enforces single-instance attachment only (one Droplet at a time); OpenStack supports multi-attach volumes.
• Volume names must be globally unique per region; OpenStack uses IDs primarily with optional display names.
• Size specified in GiB (binary) with 1 GiB to 16 TiB range; OpenStack typically GiB but flexible.

Persistent Diskhigh

• Uses Google Compute Engine REST API instead of OpenStack Cinder API.
• Offers multiple performance tiers (pd-standard HDD, pd-balanced SSD, pd-ssd, pd-extreme) with performance scaling linearly with provisioned size, unlike Cinder's backend-dependent performance.
• Supports regional disks replicated synchronously across 2 zones for higher availability (better than 99.9999% durability), while Cinder volumes are typically zonal unless using replication features.
• Online resize to increase size without detaching; no manual striping/RAID needed as GCP handles distribution automatically.