Do Private Blockchain Testbeds Still Matter? An Empirical Comparison of a Hyperledger Besu QBFT Testbed and Local Ethereum Execution Backends

Starting a private blockchain testbed takes hours; starting a local Ethereum backend takes one second. Tools such as Anvil, Hardhat Network, Ganache, and the EthereumTesterProvider of web3.py each deliver a fully functional EVM, pre-funded accounts, and a JSON-RPC endpoint instantly, with no containers, genesis configuration, or consensus parameters required. This raises a question that prior work has not answered: does a multi-node private blockchain testbed still justify its engineering cost? Testbed studies benchmark permissioned platforms against one another but, to our knowledge, never against the lightweight backends practitioners reach for first. We close this gap through controlled measurement. We construct a containerised Hyperledger Besu 23.4.1 testbed running QBFT consensus across four validators with integrated observability, then replay an invariant smart-contract workload of identical bytecode, constructor arguments, and accounts across five local backends and the testbed on a shared host. An observational analysis covers 11,397 unique block-height transitions, recovered from 74,427 per-node log observations across two corpora collected eleven months and one processor architecture apart. Local backends returned deployment receipts 341 to 3190 times faster than the consensus-bound testbed, but that speed is purchased by omitting properties a deployment target possesses. A phase-controlled experiment shows why: inclusion latency on the testbed is governed entirely by where a submission falls within the block period (L=5.009−1.012ϕ, R2=0.9998), so the comparison measures scheduling semantics rather than execution speed. No local backend produced a block while idle, exposed peer state, or surfaced transaction-pool or permissioning data. Across four contracts spanning 339 to 7408 bytes of initialisation code, every default-configured backend charged more gas than the testbed by exactly the EIP-3860 initcode surcharge of two gas per 32-byte word, from 22 to 464 gas, so the divergence is systematic and predictable though small in relative terms (<0.04%). Across five independent crash-fault trials, removing one of four validators left 68.6% of blocks unaffected while delaying 31.4% to 15.015±0.057 seconds, exactly the configured request timeout beyond the normal interval; removing a second halted the chain in every trial, with liveness restored after 83.2±4.0 seconds. The testbed occupies 3318 MiB and 36% of one host’s CPU against 12–13 MiB and 0.12% for a local backend. The block interval held at means of 5.0018 s and 4.9988 s across both deployments, indicating cross-architecture reproducibility. The two families are complementary: local backends validate contract logic rapidly and cheaply, while a private testbed remains necessary for network-level behaviour, gas fidelity, permissioning, and liveness under validator loss.