Deleting Content

I discovered this project this afternoon and I’m thinking through the process. As I read up on it, I see the word “permanent” a lot but as I read into it more it seems that if I’m running an IPFS node, I add something to my node, then I remove my node without anybody requesting my file, wouldn’t that make the file unavailable? Functionally that sounds like a delete process to me. Or even if somebody requests my files, if they GC without pinning my content then it would be gone forever.

In short, if content isn’t pinned on any server, wouldn’t GC eventually remove the file from the network?

Personally I dislike the fact that the IPFS website uses the term “permanent web” because it’s confusing. It’s using the term “permanent” because an IPFS link permanently references the content that it points to. This does not mean IPFS makes the content permanently available. As you point out, it’s up to you or the other people who care about that data to hold onto copies of the it. If nobody holds onto a copy, the data will go away. The link will still permanently point to it, but the data might not be there to retrieve.

The choice is between HTTP - a brittle system with volatile links vs. IPFS - a resilient system with permanent links. The use of content addressing does not make the web’s content permanent but it does make the links permanent while providing a plethora of powerful, dynamic ways to make data durable. Content addressing makes the system resilient, but not permanent. By contrast, HTTP links point to a location, which makes the system both brittle and volatile.

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In which situation the link exists but the content does not exist on any of the IPFS node? Usually how many copies of content exist on IPFS network?

If not I am wrong is not possible as today to know the number of replicas. The content reside on a cache till this cache is not removed. I think that only a node can decide when to pin the file permanently.
We need to wait the Filecoin

valeriano-cossu, please correct me if I am wrong. I thought filecoin was already online and running. The Filecoin is being listed on coin exchange.

This is not accurate.

There is no API to know for sure. Put you can have a lower bound by asking for peer having a copy of the data on the DHT.

The original provider of the data will ipfs add theirData. This means

that it will advertise on the DHT “hey guys, if you want a copy of the data corresponding to this hash, I can sent it to you”. Adding will also automatically pin the data on this node, meaning this node will never garbage collect it, and will keep it available until it’s unpinned.
Any other node can request the data. The canonical way to do that is to query the DHT, that will give you addresses of peers with content. At first, only the original publisher will have it. Once the querying nodes have the data, they got 2 choices: making it available until it’s garbage collected (meaning while the data is its own cache) or pin it, to keep it on its node.
When a third peer asks for this data, the DHT will give it the addresses of the 2 previous nodes. And so on.

Please take note that you pin data on a node. The same piece of data can be pinned by node A and not by node B.

Any node can decide to pin the content (on itself).

From a publisher’s point of view, once the data has been requested and sent, a copy is out there, and there is no way to control its propagation.

More generally, with any information, on any technology, once someone you have no control over has a copy, you can’t control how this information will be shared.

When a piece of data was published, the CID (~hash) of the content was published, but no one online has a copy of it anymore, either because it’s not pinned and not in cache, or because nodes having it are online.

Content is not replicated automatically. It is if a lot of nodes asks for the content (it is popular) or if they pin it (either because they like it or because you pay them to do so: we call that a pinning service).
Filecoin will be a decentralized pinning service.

Filecoin is in alpha, an alphanet is online and a testnet will be on Dec 11. You can’t use you filecoins (FIL) to rent storage space yet. At this point, it’s still speculation before the main launch
The mainnet is expected Q1 2020.

The Filecoin token is not yet live and cannot directly be traded. Those exchanges may be listing Filecoin futures but trading of Filecoin futures isn’t mediated by the Filecoin blockchain and is likely subject to additional legal constraints (IANAL).