Downloader

Is a service which does download and seed historical data.

Historical data - is immutable, files have .seg extension.

Architecture

Downloader works based on <your_datadir>/snapshots/*.torrent files (etl-tmp and snapshots directories MUST be on same drive). Such files can be created 4 ways:

• Erigon can do grpc call downloader.Download(list_of_hashes), it will trigger creation of .torrent files
• Erigon can create new .seg file, Downloader will scan .seg file and create .torrent
• operator can manually copy .torrent files (rsync from other server or restore from backup)
• operator can manually copy .seg file, Downloader will scan .seg file and create .torrent

Erigon does:

• connect to Downloader
• share list of hashes (see https://github.com/ledgerwatch/erigon-snapshot )
• wait for download of all snapshots
• then switch to normal staged sync (which doesn't require connection to Downloader)

Downloader does:

• Read .torrent files, download everything described by .torrent files
• Use https://github.com/ngosang/trackerslist see ./trackers/embed.go
• automatically seeding

How to

Start

downloader --datadir=<your_datadir> --downloader.api.addr=127.0.0.1:9093
erigon --downloader.api.addr=127.0.0.1:9093 --experimental.snapshot

Limit download/upload speed

downloader --download.limit=10mb --upload.limit=10mb

Print info_hashes in format compatible with https://github.com/ledgerwatch/erigon-snapshot

downloader info_hashes --datadir=<your_datadir>

Force re-calculate info_hashes and print in format compatible with https://github.com/ledgerwatch/erigon-snapshot

// will re-read all .seg files (high disk IO)
// also does remove and create .torrent files
downloader info_hashes --datadir=<your_datadir> --rebuild

Create new snapshots

rm <your_datadir>/snapshots/*.torrent
erigon snapshots create --datadir=<your_datadir> --from=0 --segment.size=500_000

Download snapshots to new server

rsync server1:<your_datadir>/snapshots/*.torrent server2:<your_datadir>/snapshots/
// re-start downloader 

Re-create all .idx files (by re-read all .seg files)

// Disk-read-intense
erigon snapshots index --datadir=<your_datadir> --rebuild

Known Issues

• RPCDaemon with --datadir option need restart to make new segments available