db.js

var levelup = require('level')
var zlib = require('zlib')
var fs = require('fs')
var through = require('through')

//hot backup

db = levelup(...)

var backingup = false
var backupfile = "./backupjson.log.gz"

process.on('SIGHUP', function() {
  if(backingup) return console.log('im already backing up')

  console.log('backup started!')

  var t = Date.now()

  // an example of backing up to a file.
  db.createReadStream()
  .pipe(through(function(obj) {
    // depending on if you store binary data your serialization method could be msgpack. 
    this.queue(JSON.stringify(obj)+"\n");
  }))
  .pipe(zlib.createGzip())
  .pipe(fs.createWriteStream(backupfile))
  .on("close",function() {
    backingup = false;
    console.log('backup complete. took ', Date.now()-t, 'ms');
  })
  
})

loadbackup.js

var split = require("split")
var through = require("through")
var fs = require("fs")
var zlib = require("zlib")
var levelup = require("level") 

var db = levelup("./db2")

fs.createReadStream("./backupjson.log.gz")
.pipe(zlib.createGunzip())
.pipe(split())
.pipe(through(function(str){
  this.queue(JSON.parse(str))
}))
.pipe(db.createWriteStream())