Understanding Storj DCS

This is a simple, high-level functional overview of the Storj DCS product and how it works.

Overview

Storj makes open-source software that anyone can run - individuals with a Network Attached Storage Device or NAS, those with desktop computers that are always on, businesses, or data centers - that allows these users to share unused disk drive space and bandwidth with the network. Our software aggregates all of that storage capacity and bandwidth to create an extremely secure, private, and durable cloud storage service for developers.

Storj makes that storage and bandwidth available as a distributed cloud object storage service for developers, with an enterprise-grade 99.95% availability, eleven 9s of durability, and S3 compatibility under the Storj DCS brand.

Peer Classes

There are 3 main components, or peer classes, on the network - Storage nodes, the application that enables people to share excess hard drive capacity and bandwidth with the network, Uplink Clients, developer tools (sometimes hosted) to upload and download data, and finally, the Satellite, a hosted set of services that handles access management, metadata management, storage node reputation, and data repair, as well as billing and payment.

The Storage Node stores data for others, and gets paid for storage and bandwidth. All data stored on storage nodes is client-side encrypted and erasure-coded.

Uplink Clients enables developers to store data on Storj DCS, handling end-to-end encryption from the client-side (by default), and erasure coding, where files are split into 80 pieces then distributed across our network of storage nodes. Each of the 80 pieces is stored on different, diverse storage nodes, with different operators, power supplies, networks, and geographies, etc. - yielding tremendous security, performance, and durability advantages. The client-side managed, end-to-end encryption combined with our edge-based access management capabilities provide easy-to-use tools for building applications that are more private, more secure, and less susceptible to a range of common attack vectors. Uplink clients include both our self-hosted and Storj-hosted S3 compatible gateways, the CLI, and the libuplink Go library and bindings.

The Satellite is a set of hosted services that handles developer account access, API access management, metadata management, storage node reputation, data audit, and data repair, as well as billing developers and payment for Storage Nodes. Storj Labs satellites are operated under the Storj DCS brand.

How it's Different

To give you a sense of how the Storj DCS service is different, it’s helpful to describe what happens with a round-trip upload and download of a file. Files are uploaded using an Uplink client, whether directly using the CLI or S3 compatible gateway, or indirectly using a tool that has integrated the libuplink library, such as FileZilla, Rclone or Restic.

What Happens When You Upload

When a file is uploaded, it’s first encrypted by the Uplink client using an encryption key held by that client. Next, it’s erasure-coded, meaning it’s broken up into at least 80 pieces, of which only 29 (any 29) are required to reconstitute a file. (The redundancy from erasure coding is far more efficient than replicating files and is technology used by most data storage systems, including DVDs, which is why you can still watch a movie even if there are scratches and fingerprints on the disk.)

The Uplink Client then contacts the satellite to get a list of Storage Nodes on which to store the pieces. The satellite returns more than 80 Storage Node addresses. The Uplink Client uploads pieces peer-to-peer, in parallel, directly to the Storage Nodes. The Uplink client stops attempting to upload pieces once 80 pieces have been successfully uploaded to at least 80 Storage Nodes.

The Uplink Client attempts a few more than 80 during the upload process to eliminate any long-tail effect and the related latency from the slowest Storage Nodes.

What Happens When You Download

When the Uplink Client downloads a file, it’s essentially the same process as an upload but in reverse. The Uplink Client requests a file from the Satellite and the Satellite returns a list of 35 Storage Nodes from which the Uplink Client can retrieve the pieces of the file. The Uplink Client starts attempting to download pieces from all 35 Storage Nodes, again, stopping once it has retrieved the 29 pieces needed to reconstitute the file after eliminating latency from the long-tail effect. The pieces are re-encoded and then decrypted by the Uplink client as only it has the encryption key.

Why Developers Love Storj DCS

Even with the sophisticated privacy and security features and the default multi-region availability, developers love Storj DCS because it's extremely easy for them to get started and build more secure and private applications.

When uploading and downloading files, a developer or app issues a simple cp command - the Uplink Client does the rest, abstracting all of the complexity of encryption, erasure coding, and distributing pieces on storage nodes to the Storj software in the background.

What's more, developers can use the Satellite Admin Console web interface or the share command with one either our CLI or developer library/SDK to abstract all the complexity of granular access management via client-side delegated authorization.