IPFS

A Distributed File Store

Usman Fazil | Block360 | Blockchain

By Usman Fazil

File Storage on the Web

The web uses location-based addressing to store and retrieve files. Let’s say we want to access a cat picture cat.png from domain abc.com. We’ll access this location (i.e abc.com/cat.png) via a web browser and in return we’ll get the cat picture. If however, the file has now been removed from the abc servers for whatever reason, we won’t be able to access the picture anymore. Now there is a possibility that someone else on the internet has a copy of that same cat picture, but we have no way of connecting with them and grabbing a copy of that picture. A lot of files on the internet may have the same name but the contents will likely be different.

IPFS Solution

IPFS is a peer-to-peer protocol for file storage with content-based addressing instead of location-based addressing. This means that to find a file, we do not need to know where it is (abc.com/cat.png), but rather what it contains (QmSNssW5a9S3KVRCYMemjsTByrNNrtXFnxNYLfmDr9Vaan), which is denoted by a hash of the content.

How IPFS Stores Files

Files are stored as IPFS objects, which is a data structure that consists of:

  1. Links — an array that links IPFS objects.
IPFS-Blockchain Block360
IPFS-Blockchain Block360

 

Does my file live forever on the network?

             Only important files are kept on the network and unimportant files are removed by the garbage collector, where the importance of a file is determined by “pinning”. By pinning a file, we mark that file as an important one so that it persists while unimportant files are only cached temporarily.

Issues with IPFS

                Now let’s talk about the challenges associated with IPFS. One of the biggest issues with IPFS is keeping files available. IPFS promises permanence but it does not promise persistence. This implies that if a file is made available by Alice and Bob accesses it; if Alice goes offline, Bob may still be able to access it if it hasn’t been deleted by the garbage collector. On the other hand, if Bob has pinned that file, it will remain accessible even if Alice’s node goes down. Pinning, therefore, is a major problem. As of writing this, there are more than a few public pinning services, so persistence comes at a cost.

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