Protocol Wars & Forks4 min readFilecoin (FIL)

Filecoin: The Storage Job That Never Ends at Upload

Filecoin’s 2020 launch gave storage providers an ongoing obligation: prove they still held what they had agreed to keep. Sealing, recurring challenges and retrieval each answer a different part of the customer’s question.

Filecoin: The Storage Job That Never Ends at Upload

3-Minute Fast Briefing

  • The ParadoxFilecoin’s mainnet went live on October 15, 2020, connecting a storage market with cryptographic proofs.
  • The Turning PointProof-of-Replication establishes a sealed replica; WindowPoSt repeatedly audits the storage commitment over time.
  • The LegacyA storage proof is not a download-speed promise. Filecoin later introduced PDP for a separate hot-storage tier.

Chronological Timeline

October 15, 2020Mainnet goes live

Filecoin announces that its mainnet has begun operating.

March 9, 2021The storage lifecycle explained

An official account distinguishes publishing a deal, activating storage and retrieving data.

May 1, 2025PDP adds hot-storage verification

Filecoin announces Proof of Data Possession live on mainnet for readily accessible data.

The Day After the Upload

Filecoin’s mainnet went live on October 15, 2020. The announcement celebrated a network where providers could earn by supplying storage, backed by cryptographic evidence. But the interesting part of the bargain began after the data arrived. A customer wanted a file kept for a period of time. A successful upload, by itself, could only describe the beginning of that job.[1]

The early storage-deal lifecycle made that distinction concrete. The client and provider agreed on terms, transferred the data and published a deal on-chain. Publication was not activation: the sector containing the data still had to be sealed and proven. It was possible to have a recorded agreement without the promised storage yet being active. The blockchain recorded the obligation; the provider’s hardware had to do the work.[2][6]

A Copy with Its Own Commitment

The first part of that work was sealing. In the Filecoin specification, Proof-of-Replication, or PoRep, binds an encoded replica to its data, its provider and the sealing context. The provider submits a compact proof to the chain. This is more demanding than announcing that a disk has free space: the proof concerns a particular replica the provider has committed to maintaining.[4]

A single initial proof leaves an obvious question: what happens tomorrow? The storage-proof specification frames the problem as challenges to sampled parts of the data, timed so that discarding the copy and reconstructing it only when asked should not be a rational shortcut. This is a cryptographic and economic design, not a person watching every byte at every instant.[3]

The Next Check Is Part of the Job

Window Proof-of-Spacetime, usually shortened to WindowPoSt, supplies the recurring obligation. In the scheme documented for the early network, a 24-hour proving period is divided into 48 deadlines of 30 minutes. Sectors are assigned to deadlines and proved in groups. This does not mean every file is downloaded and checked in full every half hour; the provider submits compact proofs for the storage due in its assigned windows.[5]

Missing a required WindowPoSt can produce a storage fault and penalties. A separate mechanism, WinningPoSt, applies when a provider is selected to produce a block. Missing that opportunity forfeits the block opportunity rather than carrying the same fault penalty. Keeping these mechanisms separate explains the deal more clearly: the routine duty to keep storage and the chance to earn a block reward are related, but they are not the same event.[5]

What the Proof Does Not Tell You

The storage commitment also needs context. Filecoin can include committed-capacity sectors containing arbitrary data rather than customer files. Proven capacity is therefore not automatically a measure of useful customer content. Likewise, a correct storage proof does not decide whether a stored document is truthful or valuable. Those are judgments about the material, outside the question the proof asks.[3][2]

There is a time boundary too. The deal-state specification distinguishes an active deal from one that has expired or whose sector has been terminated. Reading “stored on Filecoin” as “kept forever” would erase that boundary. Preservation still requires someone to arrange an appropriate term and continued service. The protocol makes a commitment inspectable; it does not remove the need to decide how long a file should survive.[6]

Keeping a File and Getting It Back

Retrieval adds another task. Filecoin’s 2021 explanation described finding a provider, agreeing on retrieval terms and transferring the data; a sealed-only copy could first require unsealing. Today’s retrieval documentation likewise describes locating providers and fetching content. Evidence that storage has been maintained does not, on its own, specify how quickly a reader will receive the file.[2][8]

That distinction later shaped another design. On May 1, 2025, Filecoin announced Proof of Data Possession, or PDP, live on mainnet for hot storage, where data stays readily accessible without PoRep’s sealing and unsealing process. It supplemented the archival approach rather than making the old obligations disappear. The lasting idea is the ongoing job: agreeing to hold a file, showing that the commitment is being kept, and delivering it when requested each need their own answer.[7]

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Sources & References

  1. [1]Source 1: Filecoin Mainnet is LiveFilecoin · 2020-10-15Accessed 2026-09-17
  2. [2]Source 2: How storage and retrieval deals work on FilecoinFilecoin · 2021-03-09Accessed 2026-09-17
  3. [3]Source 3: Proof-of-StorageFilecoin specificationAccessed 2026-09-17
  4. [4]Source 4: Proof-of-Replication (PoRep)Filecoin specificationAccessed 2026-09-17
  5. [5]Source 5: Proof-of-Spacetime (PoSt)Filecoin specificationAccessed 2026-09-17
  6. [6]Source 6: Storage Deal StatesFilecoin specificationAccessed 2026-09-17
  7. [7]Source 7: Introducing Proof of Data Possession (PDP): Verifiable Hot Storage on FilecoinFilecoin · 2025-05-01Accessed 2026-09-17
  8. [8]Source 8: How retrieval worksFilecoin DocsAccessed 2026-09-17
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