Adaptive Block Caching (ABC) - User Guide – Egnyte

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.

- The feature is currently available only for Windows. For Mac OS, contact the Egnyte Customer Success Manager.
- ABC is available only for domains with the Specialized File Handler add-on or on the new AEC plans (AEC Essentials, AEC Elite, AEC Ultimate).

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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
- Notifications will be shown at the start and end of the caching activity, mentioning the number of files and the amount of data cached.

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

Cache Utilization Status

The amount of disk space currently used by ABC caching is shown directly in the application's status bar. This helps users see how much local storage their cached files are consuming at a glance, and view a breakdown across all their connected profiles on hover.

Clearing Cache

The Clear Cache option releases disk space used by these cached files without changing the configured cache size or affecting cloud-stored data.

The Clear Cache option is recommended in the following situations:

To free up disk space for other applications
After completing a large project, cached files are no longer needed
After temporarily increasing the cache size for a large file

Steps to Clear Cache:

Open Desktop App > Settings > Drives > Three-Dot Menu.
Click Clear Cache. A confirmation dialog appears.
Click Clear Cache to confirm or Cancel to abort.

Things to Note during Cache Clearing Progress:
- Cache utilization indicator updates as space is released.
- In-progress uploads do not get cancelled.
- Files that are open by the user or running in the background are retained.
- Clearing cache does not delete cloud data; files can be re-downloaded on next access.

Once done, a notification of the cache clean-up being complete will be shown as a popup in the desktop app or through a Windows system notification. Afterwards the Clear Cache button is re-enabled.

Cache clearing stops when the user quits the app, when the device undergoes a Shutdown/Restart/Sign Out, or when the drive is disconnected. It can be restarted manually. Cache also gets cleared by removing and re-add the Egnyte drive for the domain.

Any cache-warming session in progress continues independently, files cached after the Clear Cache action are not evicted.

Metadata Sidecar

Users can now view rich media metadata directly from an ABC (Adaptive Block Caching) drive using Egnyte Actions, without opening the file or downloading its full contents. When accessing a supported media file, the Desktop App retrieves a lightweight sidecar file containing read-only technical attributes — including codec, resolution, frame rate, duration, and other relevant media properties.

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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.