GitHub user daviftorres edited a comment on the discussion: What does Snapshots, Backups, and Incremental Snapshots mean in CloudStack
**Instance Snapshot** Volumes in CloudStack can be linked or unlinked, and it’s important to understand the difference. **Linked Volumes** - These volumes are externally linked to the template image. - Essentially, the volume acts as an overlay on top of the template, similar to an external snapshot backed by the template. Example: Linked Volume deployed from Thin Provisioning offer. <img width="906" height="507" alt="image" src="https://github.com/user-attachments/assets/5a1ffaac-38fe-4572-9e0b-d3c8d9af8a55"; /> Here, the instance’s volume file is layered on the template image. Example: Linked Volume deployed from Thin Provisioning offer and 2 Instance Snapshots. <img width="1181" height="761" alt="Screenshot 2026-01-23 150803" src="https://github.com/user-attachments/assets/94802025-adcf-4dcf-8324-7068c6ec3def"; /> **Unlinked Volumes** These volumes are standalone files, independent of any template. Example: Unlinked Volume deployed from ISO <img width="906" height="263" alt="image" src="https://github.com/user-attachments/assets/40d2c4ee-6d0f-40a0-a4d1-1be4e1807cc0"; /> Example: Unlinked Volume deployed from Sparse Provisioning. <img width="735" height="301" alt="image" src="https://github.com/user-attachments/assets/3ccbe735-7007-4922-8abf-ef2b0d8bf4b9"; /> Example: Unlinked Volumes with Internal Snapshot <img width="908" height="307" alt="image" src="https://github.com/user-attachments/assets/9d2b4dc3-3f99-4ab4-a0db-6c7ff062a11e"; /> **Note:** Mixing internal and external snapshots is not recommended. This is where the ROOT disk provisioning type is typically configured, at the **Compute Offering**: <img width="725" height="603" alt="image" src="https://github.com/user-attachments/assets/ef9fb63f-72f2-4e8d-8eaa-6b8b48ca805b"; /> And also at the **Add Disk Offering** creation: <img width="445" height="71" alt="image" src="https://github.com/user-attachments/assets/62c5f5c8-6bfa-491e-b963-31cbe03cf796"; /> Provisioning types explained - **Thin Provisioning** - Linked Clone - Instances are created as linked clones. - The template cannot be removed while instances depend on it. - If the template becomes corrupted or inaccessible, **ALL dependent instances will also fail**. - **Sparse Provisioning** - Full Copy (Lazy Thick) - A full copy of the original image is created (not linked). - Disk space is allocated, but zero blocks are written on demand. - Faster to create than Fat provisioning. - **Fat Provisioning** - Full Copy (Eager Thick) - A full copy of the original image is created (not linked). - All disk blocks are fully zeroed at creation time. - Slower to create, but disk is fully initialized upfront. GitHub link: https://github.com/apache/cloudstack/discussions/12475#discussioncomment-15564337 ---- This is an automatically sent email for [email protected]. To unsubscribe, please send an email to: [email protected]
