Oracle Cloud Infrastructure’s (OCI) Block Volume feature allows users to attach a block volume to multiple compute instances. This is a great improvement from the previous limitation of being able to attach block volumes to only one compute at a time. This makes it easy to design Cloud solutions and lowers storage costs.
The diagrams here show how Block Storage can be shared in the read-write mode (shown on the Right) and in the read-only mode shown on the left side.
Figure 1: Sharing Block Storage in Read-Write Mode
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More about OCI Block Volume:
- Default attachment from Compute is non-shareable with exclusive read/write
- Options include “Read/Write Sharable” and “Read-Only Sharable” in contrast other vendors provide only Read-Only block volumes and there are limitations for shareable Read-Write attachments
- Read-only attachments are available in sharable mode for multiple instances
- Concurrency access control or cluster-ware solution for Read-only sharable block volume across multiple readers not needed
- Volume groups, disk-to-disk Clones, and automated backups are available for shared block volumes
- Available in all regions via OCI Console, CLI, SDK, and Terraform
Figure 2: Block Volume Options
Possible Use Cases
Sharing block volumes with multiple instances can be useful in various deployments and system designs, as shown below:
- Shared Files System for Databases
- Centralized Log files for Distributed System
- Shared Catalog with Single Writer/Multiple Readers
- Shared Disk for Patching