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VM Disk Discard#

The Discard option on a VM Disk in VergeOS is responsible for managing unused storage blocks by issuing TRIM or DISCARD commands. When Discard is enabled, the system automatically frees up unused blocks, helping to maintain efficient storage usage on the vSAN.

Enabling or Disabling Disk Discard#

When creating or editing a VM disk, you have the option to enable or disable Discard. By default, Discard is enabled, and it is highly recommended to leave it enabled for optimal storage efficiency. When Discard is disabled, deleted files on the virtual disk do not immediately free up the corresponding storage, leading to potential overuse of storage resources.

Here’s what happens when Discard is enabled:

  • The system periodically identifies and frees unused disk blocks.
  • vSAN storage remains optimized, as unused blocks are reclaimed.
  • Disk space usage more accurately reflects the actual data stored on the VM.

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Only disable Discard for performance reasons

Disabling Discard can lead to storage inefficiencies and should only be done for specific performance-related reasons. Always consult with VergeOS Support before disabling this feature.

Why Use Disk Discard?#

  • Efficient Storage Management: When a file is deleted from a VM, the unused blocks are immediately flagged as free, allowing the vSAN to reuse that space for other data.
  • Improved Disk Performance: Discard operations help maintain a clean and optimized storage system, reducing overhead from managing fragmented or unused blocks.
  • Space Reclamation: Particularly in environments with high storage churn (i.e., frequent file creation and deletion), Discard ensures that space is consistently reclaimed, avoiding storage bloat.

When to Disable Disk Discard#

In rare circumstances, you may need to disable Discard to improve performance, particularly on certain workloads where the overhead of issuing TRIM/DISCARD commands may cause delays or slowdowns. Before making this change, it's critical to understand the trade-offs in terms of storage efficiency and consult with VergeOS Support for further guidance.

By keeping Discard enabled, you ensure that VergeOS optimizes storage for virtual machines, maintaining high efficiency and minimizing wasted space.

Document Information

  • Last Updated: 2024-08-29
  • vergeOS Version: 4.12.6