A bit late to the party, but I just tried #12653 and noticed some non-intuitive behavior (on macOS), that's probably worth explaining release notes and help.

Before this new feature I kept the entire datadir on an SSD drive, so I launch with: `bitcoind -datadir=/Volumes/SSD/Bitcoin`.

Initially I naively moved `/Volumes/SSD/Bitcoin/blocks` to `/Users/bitcoin/blocks` and added a line to `/Volumes/SSD/Bitcoin/bitcoin.conf`: `blocksdir=/Users/bitcoin/blocks`.

I then realized that I shouldn't have moved the `index` subdirectory, so I moved that back to `/Volumes/SSD/Bitcoin/blocks/index`. Having an empty `blocks` dir with just and `index` subdir is a bit weird. Perhaps after @jimpo's #11857 is merged, we could just move / assume all indexes to be there (if `-blocksdir` is set)?

Worse, it created a directory `/Users/bitcoin/blocks/blocks`, which seems like a bug. I had to set `blocksdir=/Users/bitcoin` instead.
}
    fCheckBlockIndex = gArgs.GetBoolArg("-checkblockindex", chainparams.DefaultConsistencyChecks());
    fCheckpointsEnabled = gArgs.GetBoolArg("-checkpoints", DEFAULT_CHECKPOINTS_ENABLED);
    hashAssumeValid = uint256S(gArgs.GetArg("-assumevalid", chainparams.GetConsensus().defaultAssumeValid.GetHex()));
    if (!hashAssumeValid.IsNull())
        LogPrintf("Assuming ancestors of block %s have valid signatures.\n", hashAssumeValid.GetHex());
    else
        LogPrintf("Validating signatures for all blocks.\n");
    if (gArgs.IsArgSet("-minimumchainwork")) {
        const std::string minChainWorkStr = gArgs.GetArg("-minimumchainwork", "");
        if (!IsHexNumber(minChainWorkStr)) {
            return InitError(strprintf("Invalid non-hex (%s) minimum chain work value specified", minChainWorkStr));
        }
        nMinimumChainWork = UintToArith256(uint256S(minChainWorkStr));
    } else {
        nMinimumChainWork = UintToArith256(chainparams.GetConsensus().nMinimumChainWork);
    }
    LogPrintf("Setting nMinimumChainWork=%s\n", nMinimumChainWork.GetHex());
    if (nMinimumChainWork < UintToArith256(chainparams.GetConsensus().nMinimumChainWork)) {
        LogPrintf("Warning: nMinimumChainWork set below default value of %s\n", chainparams.GetConsensus().nMinimumChainWork.GetHex());
    }
    
    int64_t nMempoolSizeMax = gArgs.GetArg("-maxmempool", DEFAULT_MAX_MEMPOOL_SIZE) * 1000000;
    int64_t nMempoolSizeMin = gArgs.GetArg("-limitdescendantsize", DEFAULT_DESCENDANT_SIZE_LIMIT) * 1000 * 40;
    if (nMempoolSizeMax < 0 || nMempoolSizeMax < nMempoolSizeMin)
        return InitError(strprintf(_("-maxmempool must be at least %d MB"), std::ceil(nMempoolSizeMin / 1000000.0)));
    
    
    if (gArgs.IsArgSet("-incrementalrelayfee"))
    {