Adaptive Block Caching (ABC) - User Guide (Limited Availability)

Adaptive Block Caching (ABC) enables the users to open, edit, and save large files faster by storing only the parts of a file they are actively using on their computer.

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Using the ABC Drive

Supported Features

Desktop App Features Available in ABC Mode

Automatic Fallback to Desktop App Classic

Current Limitations in ABC Mode

Additional Resources

 

Using the ABC Drive

Once the ABC drive is configured:

• The drive appears in File Explorer like a normal Egnyte drive.
• Users see the same folder structure; existing drive letters are preserved if a classic drive was upgraded. 
• Opening a supported file downloads only the necessary blocks; navigating within the file (for example, another sheet, viewport, or sequence) downloads additional blocks on demand. 
• Saving the file uploads only modified blocks, improving performance and reducing bandwidth usage.

Supported Features

Cache Warming

For users who plan to work on specific projects in advance (such as a CAD folder or video project), the cache can be warmed by adding the folder. ABC supports this through the Add to Cache option.

• Right-click a file or folder → Egnyte Actions → Add to Cache
  • For a file: downloads and caches that file
  • For a folder: attempts to pre-caches all files in that folder, following limitations apply
    • Maximum number of files: 10000 files
    • Maximum number of folders: 10 folders
    • Maximum size of data which can be downloaded during a single cache warming action: 50GB
  • Notification will be shown at the start and end of the Caching activity
    
    

Cache Warming Best Practices

• Fully cached files display the same visual indicator as files marked for offline access, as they are currently available locally and can be opened while offline. This indicator does not guarantee permanent local availability, as cached files may be evicted over time
• Files are cached not only through explicit cache-warming actions but also during normal file access, and those files will also show this indicator
• Pre-cached files are not permanently pinned; they still follow eviction rules once cache fills up. 
• Folder-level indicators are not shown, and the user may need to refresh the Windows Explorer window to see updated indicators
• If pre-caching cannot complete caching all files (in cases such as insufficient disk space or cache capacity), the app shows the end user notification and fails gracefully without data loss
• The Add to Cache option remains available even if files are already cached, since they may have been evicted and users may want to re-cache them
• While caching is in progress Add to Cache is disabled
• Cache warming supports a maximum of 10 selected folders at a time. All subfolders under those folders are included without limitation

Clearing Cache

The Adaptive Block Cache (ABC) can be cleared by removing and re-add the Egnyte Drive for the domain; this automatically clears the cache associated with that domain.

When to Clear the Cache:

Clearing the cache may help resolve issues such as full disk space, stale file data, unexpected file behavior, or troubleshooting scenarios where cached content needs to be refreshed. After clearing the cache, files will need to be re-cached during normal use, which may result in slower file opening performance until the cache is rebuilt.

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Desktop App Features Available in ABC Mode

File Explorer and UI

• Upload progress for files added to an ABC drive appears in the Uploads tab of the Desktop App. 
• Right-click Egnyte context menu supports: 
  • Share (including Copy Link) 
  • View Online 
  • Ask a Document (for supported file types) 
  • Create Shortcut (with limitations; see below) 
  • Egnyte Actions and other 3rd-party integrated actions (such as Send with Adobe Sign and Share in Slack) when appropriate. 

Sync Status Actions

• If a file is unsynced or not yet uploaded, cloud actions (like share link) may be disabled or show a clear explanatory message. 
• Temporary or skipped files automatically hide incompatible Egnyte context menu items to avoid errors. 

Integrations

ABC integrates with online editing and co-editing services even when files sit in local cache: 

• Microsoft 365 
• Google Workspace 
• Microsoft Office Co-Editing

File Locking

Egnyte provides the metadata and permission checks so that: 

• The same collaboration experience works as if the file were opened from the cloud. 

• Locking is respected: 
  • Collaboration locks allow co-edit
  • Regular Egnyte locks block co-edit and show who locked the file
  • If the user themselves locked the file, they must unlock it first

• Users may see clear messages such as: 
  • “File is locked by another user” 
  • “File not uploaded yet” 
  • “Offline mode not supported for co-edit”

Connected Folders

• Connected Folders allow users to link local folders on their Windows device (such as Desktop, Documents, or application-specific working folders) to a corresponding folder in Egnyte Cloud
• Connected Folders are supported and behave the same as in Desktop App Classic mode, with files synchronized bi-directionally between the local folder and the cloud
  

Security and Remote Capabilities 

• Admins can revoke drive access: When Desktop App detects 401 (Unauthorized), the application disconnects the drive, removes tokens, and informs the user they must re-authenticate
• Admins can optionally issue a Remote Wipe: The app unmounts all drives associated with that device and securely deletes cached Egnyte data so nothing remains on disk

Skipped File Handling 

When a file cannot be uploaded (in cases such as permissions, lock, file size validation, blocked extension, and more): 

• The user receives a notification with the reason
• The Home widget shows the count of skipped files and allows moving them to a local desktop folder
• Example causes: 
  • Backend 403 or 409 errors (such as permission denied, file locked, unsupported Google file)
  • Blocked extensions defined by domain admin (for example, .exe, .eml, .qbb)
• Skipped files remain accessible locally and are marked unsynced (red indicator)
• Once the underlying issue is fixed (for example; extension changed to allowed), upload resumes automatically and the file disappears from the skipped list

Temporary or system files may be filtered and skipped silently to avoid noise. 

Command Line Interface

Ability to mount a drive and perform operations on it via a Command Line interface is supported with ABC

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Automatic Fallback to Desktop App Classic

If ABC encounters an unrecoverable error, the Desktop App can automatically fall back to Classic mode. In this situation:

• The user sees a pop-up explaining that the app is attempting to recover
• The drive may be unavailable for a few minutes
• During recovery, the tray icon and widget indicate a special recovery state

Once recovered, the user gets a notification that the drive is now running in Classic mode. 

The app stays in Classic until: 

• The user restarts the app (depending on policy) 
• The app is upgraded and ABC is re-enabled according to configured fallback policy

This ensures users keep access to their data even if there’s an issue with ABC. 

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Current Limitations in ABC Mode

ABC is still evolving and does not yet have full parity with Desktop App Classic. As a result, ABC will show clear messages and offers a path back to Classic when needed.

Context menu actions include:

• Offline Folders
• Create shortcut

For example, certain items may appear in the context menu, but when used on an ABC drive they show a message: 

Users can either choose Cancel or Switch Drive to Classic Mode.

Application UI Features 

Some UI features are visible but not fully functional in ABC mode, for example: 

• Offline Folders Tab - ABC folders cannot be marked for offline, so ABC folders will not be present in this tab
• Bandwidth Throttling Settings - This setting does not impact ABC drive
• Open links in Desktop App routing is not available for ABC drives
• Advanced option is not available In three-dot drop down menu against ABC drive

General Limitations 

These do not usually show a UI, but are important to know: 

• Manual Offline Mode - Offline mode support for ABC is not available
• Egnyte Shortcuts - Not Available
• Fixed Folders or Protected Directories - Advanced deletion-protection (for example, used by some regulated customers) is not fully validated in ABC
• Metered Connections - Automatic offline switching when Windows marks a network as metered is not yet available to ABC.
• Bandwidth Throttling - Classic Desktop App’s per-direction throttling for sync traffic is not currently exposed for ABC
• Desktop Configurations for ABC - Admins cannot yet mass-provision ABC drives using Desktop Configuration Profiles; large-scale deployment support is tracked but not released
• Custom Upload Policy for Large Files - Legacy behavior that uploads large files directly from local cache is not yet tuned for ABC; future Smart Cache protocol improvements may replace this
• Custom Lock Policies - Some advanced lock-skip rules (such as for offline or private folders) may not yet be configurable; ABC’s Smart Cache component owns locking logic and is still being aligned
• Real-Time Event Delivery (RED) - Real-time event notifications to the Desktop App are limited; additional work is required for full instantaneous status updates across all ABC scenarios

Other Known Limitation

When using Adaptive Block Cache (ABC), listing folders with very large numbers of items (approximately 10,000+ files or subfolders) may take longer than expected due to backend directory listing behavior. Improvements to optimize listing performance is planned for a future release.

File & project size tested limits

• Base file size: up to ~1 GB 
• External references (Xrefs): Up to ~400 (≈100 MB each, including individual 20 GB xrefs)
• Concurrent collaborators: ~5 users per project

These guidelines reflect the configurations we have internally validated and are currently supported for reliable performance.

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Additional Resources

Adaptive Block Caching Overview

Adaptive Block Caching FAQs  

Desktop App Overview

Desktop App Installers

Desktop App Installation for Windows

Desktop App Limitations

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