Adaptive Block Caching (Limited Availability)

Overview

Adaptive Block Caching (ABC) is a next-generation caching technology built into the Egnyte Desktop App, designed to transform how teams work with large and complex files by intelligently streaming and syncing only what is necessary for a given period of time. This means faster file access, smoother performance, and a more responsive experience.

• ABC defers downloading and uploading entire files.
• When a user opens a file, it downloads the parts (block) of the file that’s needed to get started.
• As a user works and saves on a file, only their changes are synced back to Egnyte.
• This results in faster access and lower bandwidth usage.
• This is especially beneficial for large project files (for example, CAD drawings, video timelines), where only parts of the file are accessed and modified. 

ABC runs entirely inside the existing Egnyte Desktop App - no separate software or hardware is needed. Existing drive letters can be upgraded to ABC without re-mapping.

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Prerequisites

Use Cases

Steps to Enable ABC

End User Experience

Configuring the ABC Cache (Location and Size)

Using the ABC Drive

Cache Warming

Disabling ABC (Switching to Classic)

Clearing Cache

Supported Applications and File Sizes

Bandwidth Recommendation

Existing Desktop App Features Available in ABC Mode

Current Limitations in ABC Mode 

Automatic Fallback to Desktop App Classic 

Frequently Asked Questions

Additional Information and Resources

 

Prerequisites

• Users should be on the Egnyte Desktop App version 4.1.0 or later for Windows
• After installation or upgrade, restart the Desktop App so it can check eligibility and offer to enable ABC. For eligible users, Egnyte drives for that domain are mounted in ABC mode instead of Classic mode. 
• All drives for a given user + domain on a device operate in either ABC or Classic mode; mixed modes are not supported.
• Files uploaded through an ABC-enabled drive are stored in block format. Existing non-block files open normally, are downloaded fully on first access, and are automatically re-uploaded in block format after being saved.

Use Cases

• Teams working with large design files (AutoCAD, Civil 3D) stored in Egnyte Cloud, where files are opened, edited, and saved repeatedly that require improved performance without downloading full files locally.
• Distributed project teams across multiple offices or remote locations accessing shared project data, where network latency impacts file open and save operation times and local caching can reduce repeated data transfers.
• Projects that rely heavily on reference files or linked models (such as AutoCAD Xrefs), where only portions of large files are accessed frequently and caching file blocks can improve responsiveness when opening or updating drawings.
• Individual users or roles (designers, engineers) who primarily work on a limited subset of very large project files on a regular basis, making block-level caching effective over time as frequently accessed data remains locally available.

Steps to Enable ABC

Once Adaptive Block Cache (ABC) is available for the Egnyte domain, the admin needs to enable ABC for users. By default no user will have access to ABC. 

User Eligibility (Group-Based)

1. Create a new user group in the web UI. Go to the left side menu > Settings > Users & Groups > Groups > Add Group
   
   
2. Name the group exactly Egnyte ABC Users and click on Save
   
3. Add all the users who want to access ABC to this group and save. It may take up to 15 mins to reflect.

End User Experience

ABC Mode Notifications 

• When a user becomes eligible for ABC a system notification appears.
  
• Welcome message on the Egnyte Desktop app appears as:
  
• Clicking the notification or the desktop welcome message opens a confirmation dialog
  
• User clicking Continue will be directed to the ABC Cache configuration flow. 

Configuring the ABC Cache (Location and Size)

When a user opts in, they see a Configure ABC Drive screen where they can change cache location: 

• Choose a cache location (internal drive only) 
  • Only internal drives are listed, sorted by drive letter with label and free space. 
  • Drives with less than 8 GB free are greyed out and cannot be selected. 

  • A non-editable path is displayed where the cache folder will live (for example, a sc_cache folder under the app’s data directory). 
    

    Once selected, the cache location is permanent for that device. In order to change the location later, users must remove all ABC drives and re-add them. 

  • Set the eviction threshold (cache size)
    • Minimum: 8 GiB 
    • Default: 50 GiB 
    • Maximum: 90% of the total capacity of the selected drive (rounded). 
    • The app validates the value as the user types and only allows numbers within this range. 
    • The eviction threshold defines how much space ABC can occupy before it starts removing least-used blocks.
  • For any additional ABC drives (for example, multiple domains or users on the same device), the cache location is reused and fixed, but each drive’s eviction threshold can still be configured separately. Existing ABC drives can adjust the threshold later via a Settings> three dots menu on the drive > Configure > Adaptive Block Caching tab in the Desktop App. 
    
    

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.

Cache Warming

For users who know they will work on specific projects (for example, a CAD folder or video project) ahead of time they can warm their cache with that folder, ABC supports Add to Cache.

• 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.

Disabling ABC (Switching to Classic)

Users have the option disable ABC themselves (unless an admin has locked drive management): 

1. Open the system tray and click the Egnyte Desktop App icon. 
2. Click the gear icon (Settings).
3. Next to the drive letter, click the three dots (…).
4. Select Disable ABC Mode.
   

If the admin has explicitly disabled drive management via Desktop Configurations, users cannot remove the drive but they can still disable ABC mode on it.

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.

Supported Applications and File Sizes

Currently Certified Applications (Initial Launch) 

• AutoCAD 

• Civil 3D 

File and Project Size Guidelines (Typical Scenarios)

• Minimum file size for ABC block caching: 1 GB
• Maximum file size for ABC block caching: 250 GB. 

• Projects size: 
  • Base file size: ~1 GB 
  • Up to ~100 external references (~100 MB each) 
  • ~5 concurrent collaborators per project 

Bandwidth Recommendation

For optimal performance with Adaptive Block Caching (ABC), a network bandwidth of 500 Mbps is recommended. Lower bandwidth may result in slower file access and longer cache build times, especially when working with large files.

Existing 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, etc.): 

• 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 (e.g., 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

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.  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.

Limited context menu actions include:

• Sync for offline access
• Create shortcut

Limited 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 are planned for a future release.

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. 

Frequently Asked Questions

Q: Do users need to re-map their drive letters to use ABC? 
A: No. When a drive for an eligible domain is upgraded to ABC, the Desktop App reuses the existing drive letter and augments it with block-caching capability. 

Q: What happens to existing files that were uploaded before ABC? 
A: They remain usable. When a user opens and edits those files via the ABC drive, they’ll be downloaded fully the first time; after saving, they’re re-uploaded in block format so further edits benefit from ABC. 

Q: Can I have one ABC drive and one Classic drive for the same domain on the same device? 
A: No. For a given domain + user + device, drives are either all ABC or all Classic. Mixed modes for the same domain on the same device are not supported. 

Q: Does ABC support offline work? 
A: No full offline-mode parity with Classic (including metered connection logic and UI controls) is not available. Manual offline mode does not impact ABC drives. In case of actual offline scenario files already fully cached would still be available for the user. Other files if accessed won’t be available and vanish from the folder on the local machine only. No impact to the cloud.

Q: What if a user is removed from the Egnyte ABC Users group? 
A: Their drives will revert to Desktop App Classic behavior. Files remain accessible; however, future activity will no longer use block-based caching. 

Q: How to contact Egnyte support for ABC
A: Use the Desktop App’s Send logs to support capability to provide diagnostic details (accessible from the app’s menu). 
 

Additional Information and Resources

Desktop App Overview

Desktop App Installers

Desktop App Installation for Windows

Desktop App Limitations