SupraSeal PC2 Setup

This is a step by step guide on how to enable the experimental SupraSeal C2 feature on your Lotus-Workers that is in the Lotus v1.25.0 release.


  • You need to have CUDA configured on your server. Check out the CUDA installation tutorial.
  • Rust installed.
  • lotus-bench installed
  • Ubuntu 22.04 LTS or higher for the server running SupraSeal PC2.
  • Lotus v1.25.1 or higher installed. Your lotus-miner and all your lotus-workers need to be built from source with the FFI_USE_FIXED_ROWS_TO_DISCARD=1 enviroment variable to use SupraSeal PC2.


Some early benchmarks with different GPUs (More coming):

GPUSpeedupCUDA (sec)SupraSeal PC2 (sec)
RTX A5000151
RTX A4000775234


  1. Install dependencies needed for building and using the SupraSeal PC2 binary
sudo apt install build-essential libconfig++-dev libgmp-dev wget git curl
  1. Checkout Lotus v1.25.1-rc1.
  2. Build from source with the environment variable FFI_USE_FIXED_ROWS_TO_DISCARD=1 exported.

Please note that you also need to export and build with this enviroment variable across the lotus-miner stack of machines. Else the SupraSeal PC2 will fail!

  1. Run the build script for SupraSeal PC2 located in the ../lotus/scripts/ folder
cd /lotus/scripts

By default, this script will build the SupraSeal PC2 binary for 512MiB and 32GiB sectors.

Run with lotus-bench:

  1. Create a folder where we can keep all the assets we need for doing the benchmark.
mkdir benchdir && cd benchdir
cp ../lotus/lotus-bench . # Copy the lotus-bench tool, used for benchmarking
cp ../lotus/scripts/supra_seal/bin/pc2 .  # Copy the SupraSeal PC2 binary, which we'll call when  doing PC2
cp ../lotus/scripts/supra_seal/demos/rust/supra_seal.cfg . # Copy the configuration file for SupraSeal

Please adjust the paths to your lotus-folder depending on where you are creating the benchdir-folder.

  1. First generate a sector with some random data, we will use a 512MiB in this benchmark:
./lotus-bench simple addpiece --sector-size 512M /dev/zero s-unsealed
AddPiece 1.613019762s (317.4 MiB/s)
baga6ea4seaqdsvqopmj2soyhujb72jza76t4wpq5fzifvm3ctz47iyytkewnubq 536870912
  1. Generate the PreCommit1 for the sector. Remember to adjust the CID and size according to your inputs and outputs from the previous step:
./lotus-bench simple precommit1 --sector-size 512M s-unsealed s-sealed s-cache baga6ea4seaqi646o3xo3mgwctpxyd5imoijluw2nm4rzwt532wcqqjqcpgvxmna 536870912
PreCommit1 2m45.338767868s (3.097 MiB/s)
  1. Now call the SupraSeal PC2 binary with the --external-pc2 flag.
GOLOG_LOG_LEVEL=debug RUST_LOG=trace ./lotus-bench simple precommit2 --sector-size 512MiB --external-pc2 './pc2 -b 512MiB -c supra_seal.cfg -i "${EXTSEAL_PC2_CACHE}" -o "${EXTSEAL_PC2_CACHE}" -d "${EXTSEAL_PC2_UNSEALED}" && rm -f "${EXTSEAL_PC2_SEALED}" && mv "${EXTSEAL_PC2_CACHE}/sealed-file" "${EXTSEAL_PC2_SEALED}"' s-sealed s-cache 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
pc2 took 3 seconds utilizing 87381.3 iOPS
PreCommit2 6.91751121s (74.02 MiB/s)
d:baga6ea4seaqdsvqopmj2soyhujb72jza76t4wpq5fzifvm3ctz47iyytkewnubq r:bagboea4b5abcbgfzry2gavrhgzhefwz3pyozaheii5kcjako55zr65zolhwmwbbq

And there you have the SupraSeal PC2 performance running lotus-bench.

Use with the lotus-worker:

You can run the lotus-worker calling the SupraSeal PC2-binary by using the --external-pc2 flag, and giving the binary the information it needs. Here is an example:

lotus-worker run --external-pc2 './pc2 -b 32GiB -c /home/lotus/scripts/supra_seal/demos/rust/supra_seal.cfg -i "${EXTSEAL_PC2_CACHE}" -o "${EXTSEAL_PC2_CACHE}" -d "${EXTSEAL_PC2_UNSEALED}" && rm -f "${EXTSEAL_PC2_SEALED}" && mv "${EXTSEAL_PC2_CACHE}/sealed-file" "${EXTSEAL_PC2_SEALED}"'

In the --external-pc2 flag, the parameters are as follows:

  • ./pc2: This is the SupraSeal PC2 binary that will be called. The binary should be located in the same directory from which the lotus-worker command is run, or in a directory that is included in the system’s PATH.
  • -b: This specifies the sector size. By default SupraSeal is built for 512MiB and 32GiB sectors. You can adjust this according to your needs.
  • -c: This is the path to the SupraSeal configuration file. It should be located in you lotus/scripts/supra_seal folder.
  • -i "${EXTSEAL_PC2_CACHE}": This is the input directory for the cache. It uses the EXTSEAL_PC2_CACHE environment variable.
  • -o "${EXTSEAL_PC2_CACHE}": This is the output directory for the cache. It also uses the EXTSEAL_PC2_CACHE environment variable.
  • -d "${EXTSEAL_PC2_UNSEALED}": This is the directory for the unsealed sectors. It uses the EXTSEAL_PC2_UNSEALED environment variable.
  • rm -f "${EXTSEAL_PC2_SEALED}": This command removes the existing sealed file if it exists.
  • mv "${EXTSEAL_PC2_CACHE}/sealed-file" "${EXTSEAL_PC2_SEALED}": This command moves the newly sealed file to the sealed directory.

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