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Blobs

In the Deneb network upgrade, one of the changes is the implementation of EIP-4844, also known as Proto-danksharding. Alongside with this, a new term named blob (binary large object) is introduced. Blobs are "side-cars" carrying transaction data in a block. They are mainly used by Ethereum layer 2 operators. As far as stakers are concerned, the main difference with the introduction of blobs is the increased storage requirement.

FAQ

  1. What is the storage requirement for blobs?

    After Deneb, we expect an additional increase of ~50 GB of storage requirement for blobs (on top of what is required by the consensus and execution clients database). The calculation is as below:

    One blob is 128 KB in size. Each block can carry a maximum of 6 blobs. Blobs will be kept for 4096 epochs and pruned afterwards. This means that the maximum increase in storage requirement will be:

    2**17 bytes / blob * 6 blobs / block * 32 blocks / epoch * 4096 epochs = 96 GB

    However, the blob base fee targets 3 blobs per block and it works similarly to how EIP-1559 operates in the Ethereum gas fee. Therefore, practically it is very likely to average to 3 blobs per blocks, which translates to a storage requirement of 48 GB.

    After Electra, the target blobs is increased to 6 blobs per block. This means blobs storage is expected to use ~100GB of disk space.

  2. Do I have to add any flags for blobs?

    No, you can use the default values for blob-related flags, which means you do not need add or remove any flags.

  3. What if I want to keep all blobs?

    Use the flag --prune-blobs false in the beacon node. The storage requirement will be:

    2**17 bytes * 6 blobs / block * 7200 blocks / day * 30 days = 158GB / month or 1896GB / year

    To keep blobs for a custom period, you may use the flag --blob-prune-margin-epochs <EPOCHS> which keeps blobs for 4096+EPOCHS specified in the flag.

  4. How to see the info of the blobs database?

    We can call the API:

    curl "http://localhost:5052/lighthouse/database/info" | jq

    Refer to Lighthouse API for an example response.