Introduction to the CTERA Edge Filer
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Introduction to the CTERA Edge Filer

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Article Summary

CTERA Edge Filers seamlessly combine collaboration capabilities, local storage, cloud storage, and data protection functionality in a single, cost-effective package. CTERA Edge Filers are available as physical or virtual appliances.

  • H-Series CTERA Edge Filers run under a VMware ESXI hypervisor on a range of physical appliances.
  • V-Series CTERA Edge Filers are software-based gateways running on a hypervisor, such as ESXi or KVM, or in a cloud, such as AWS.
  • X-Series CTERA Edge Filers run on hyperconverged physical appliances providing high availability and efficient disaster protection.

CTERA Edge Filers replace file servers and other traditional file storage solutions with a single, cloud-integrated and cost-effective solution.
CTERA Edge Filers:

  • Incorporate Intelligent caching technology.
  • Deliver unlimited file access to office users, with visibility to all organizational files centralized in the cloud, either private or public.
  • Provide users with collaboration across offices and endpoints with no local storage restraints.
  • Dynamically cache files from a secure CTERA Portal to the CTERA Edge Filer.
    The CTERA Edge Filer is managed using a web-based interface or centrally through the CTERA Portal. The CTERA Portal also allows users to sync content between the CTERA Portal and the CTERA Edge Filer, as well as between CTERA Edge Filers located in different branch offices.

The CTERA Edge Filer connects to a CTERA Portal to provide the following:
CACHING (Caching Gateway) – Provides users with LAN speed access to all their home folders and shared folders on the CTERA Portal. Local user accounts are mapped to the equivalent user accounts in the cloud, so that each user sees only his or her personal view of the cloud files. Users can access locally stored, synced copies of the folders they are allowed to access on the CTERA Portal.
The main storage is on the CTERA Portal in the cloud with stubs saved on the CTERA Edge Filer. A stub is a file with a tiny footprint that contains the metadata about the file, such as the file name, size, and modification date. Only the folder and file metadata and not the actual file content is saved locally. This results in the cost of storage being significantly lower. Also, systems with many file changes, where only some of the files are required locally, don’t over use bandwidth between the cloud and CTERA Edge Filer. Only the required files are passed across the wire.
When a user accesses a file stub, the file is downloaded and opened without delay, and where possible, large files are streamed from the cloud so they can be accessed faster. After the download has completed, the file is unstubbed. Any changes to the file are synced back to the CTERA Portal. Folders that are always required can be pinned, in which case the files in the folders, and not the stubs, are stored on the CTERA Edge Filer.
CLOUD BACKUP – Provides secure periodic point-in-time backups of local folders and files on the CTERA Edge Filer that are not cached with a CTERA Portal. Automated differential backup and restore functions include block-level deduplication, compression, and encryption technologies, ensuring secure and efficient synchronization between the CTERA Edge Filer and the CTERA Portal. Backups are encrypted using high-grade AES encryption and encoded to maximize bandwidth utilization. Users can recover backed up files.


CLOUD BACKUP requires a backup license from CTERA.

Business Continuity After a CTERA Edge Filer Fails

If an CTERA Edge Filer fails, after setting up a replacement, the metadata from the CTERA Portal is downloaded quickly so the stub files are almost immediately available on the replacement CTERA Edge Filer. Both metadata and data are populated to the replacement CTERA Edge Filer based on priority: When a path is entered to access content, that content receives download priority.

Deduplication on Edge Filers

CTERA edge filers support file-level deduplication that reduces physical cache storage and improves performance when accessing stub files that already exists as another file on the edge filer.

Files with the same content are linked to the same on-disk data, instead of taking twice the disk space. A deduped file, upon being modified, is populated with the underlying data.

Files are deduped:

  • During a copy and paste operation in Windows File Explorer or Mac Finder.
  • After a file is modified locally, during the upload to the portal, the file will be deduplicated with a local copy of the data, if one exists.
  • If a local copy exists before a download starts, deduplication is immediate and the file is not downloaded, saving the network traffic.

Local file-level deduplication requires Edge Filer version 7.3.x and higher.
Local deduplication is reported in the Cloud Sync log.


A restart is required after enabling or disabling deduplication.

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