Meta: Off-chain data

[Stebalien]

While users can coordinate storage of large datasets with Filecoin, actors can't directly access this state as it's not universally available.

However, that doesn't mean the data is completely inaccessible. We have several options for accessing state stored in Filecoin sectors:

1. Bounties.
2. Side-chains.

But the important question is: why? Access to off-chain data means actors can make decisions based on very large datasets that couldn't fit on-chain. This is primarily useful when most of the dataset will never be accessed by the chain.

In most cases, a viable alternative is to ask the message sender to provide the necessary data to complete the operation. However, this isn't always possible:

1. The message sender may not have ready access to the data.
2. The storage provider may be more willing to fulfill a bounty than to serve a retrieval request for a few blocks. A bounty can be fulfilled through normal Filecoin messages and doesn't involve directly serving data to a client.
3. The operation may not be directly triggered by a user message (we've discussed things like cron and async tasks in the past).

[aronchick]

I think an interesting clarification detail here is WHY actors would need access - because they want to interact with the data? validate it? etc