Summary
The current vSAN documentation references "caching" in several places but never clearly explains what caching the vSAN does or doesn't do, which leads to customer confusion — especially for those coming from traditional SAN/HCI platforms that use explicit SSD read/write cache tiers.
Current State
Caching is mentioned vaguely across multiple pages without a consistent explanation:
product-guide/storage/vsan-architecture.md lists "block-level cache management" and "frequently accessed data optimization" without defining the mechanismproduct-guide/cluster-settings.md references a "storage buffer per node (default 2 GB)" for "vSAN performance caching" with no further detailproduct-guide/virtual-machines/vm-best-practices.md says the vSAN handles "disk performance functions, caching, etc." automaticallyproduct-guide/storage/vsan-diagnostics.md documents a vcmd cache info command and read-ahead caching stats but doesn't explain what they measure
What's Missing
- Does the vSAN use a traditional read/write cache layer (e.g., SSD as cache for HDD)?
- How does the "storage buffer per node" RAM allocation relate to I/O caching?
- What role does Tier 0 (metadata tier) play beyond dedup hashmap storage — does it cache hot data?
- How does read-ahead caching work and when is it active?
- Is tiering the caching strategy (i.e., preferred tier placement replaces a traditional cache layer)?
Why This Matters
Customers evaluating or deploying VergeOS — particularly those migrating from VMware vSAN or other HCI platforms — expect to understand caching behavior for capacity planning and performance tuning. The current docs leave them guessing.
Suggested Approach
Add a clear section to vsan-architecture.md (or a dedicated page) that explains:
- Whether the vSAN uses a discrete cache layer or relies on tier placement
- The role of the per-node storage buffer (RAM-based I/O buffering)
- How read-ahead and block-level caching work in practice
- How this differs from traditional SAN/HCI caching models
This will likely require input from engineering to document accurately.
Summary
The current vSAN documentation references "caching" in several places but never clearly explains what caching the vSAN does or doesn't do, which leads to customer confusion — especially for those coming from traditional SAN/HCI platforms that use explicit SSD read/write cache tiers.
Current State
Caching is mentioned vaguely across multiple pages without a consistent explanation:
product-guide/storage/vsan-architecture.mdlists "block-level cache management" and "frequently accessed data optimization" without defining the mechanismproduct-guide/cluster-settings.mdreferences a "storage buffer per node (default 2 GB)" for "vSAN performance caching" with no further detailproduct-guide/virtual-machines/vm-best-practices.mdsays the vSAN handles "disk performance functions, caching, etc." automaticallyproduct-guide/storage/vsan-diagnostics.mddocuments avcmd cache infocommand and read-ahead caching stats but doesn't explain what they measureWhat's Missing
Why This Matters
Customers evaluating or deploying VergeOS — particularly those migrating from VMware vSAN or other HCI platforms — expect to understand caching behavior for capacity planning and performance tuning. The current docs leave them guessing.
Suggested Approach
Add a clear section to
vsan-architecture.md(or a dedicated page) that explains:This will likely require input from engineering to document accurately.