Erigon Datadir Operations

Duplicating a Datadir

Given a source path and destination path, follow this procedure exactly.

Precondition Checks

All checks must pass before copying. Abort on the first failure.

1. Source exists: test -d <src> — abort if missing
2. Source is a valid Erigon datadir: verify all three exist:
   • <src>/nodekey (file)
   • <src>/snapshots/ (directory)
   • <src>/chaindata/ (directory)
3. Destination does not exist: test ! -e <dst> — abort if it already exists
4. Destination parent is writable: test -w "$(dirname <dst>)" — abort if not
5. Report source size: run du -sh <src> and always tell the user the size before proceeding
6. Detect APFS: find the mount device for the destination parent directory from mount output. If the mount entry contains apfs, use the APFS CoW procedure below; otherwise use the full-copy procedure.

APFS Procedure (copy-on-write)

Use this when the destination is on an APFS volume.

1. Run cp -ac <src> <dst> — this creates a CoW clone that is near-instant and consumes no extra disk space.
2. No disk space check is needed for CoW clones.
3. After the copy completes, delete chaindata from the destination: rm -rf <dst>/chaindata

Other Filesystems Procedure (full copy)

Use this when the destination is NOT on APFS.

1. Check disk space: run df -h "$(dirname <dst>)" and compare available space to the source size. If available space is less than source size, abort and tell the user — do not proceed.
2. Run cp -a <src> <dst> to recursively copy the entire datadir. This is a long-running operation for large datadirs — run in background.

Post-Copy

After either procedure completes, confirm success by listing the destination contents and comparing against the source (minus chaindata/ for APFS copies).