Live Blockchain Backup What is a good strategy for backing up bitcoind's blockchain files (not its wallet file) without having to take (e.g.) a bitcoind that is powering a counterparty-server instance offline?

Copying the blockchain from a running bitcoind may result in a corrupted copy (https://bitcoin.stackexchange.com/a/25260/1660),

To avoid this, is it best to run a separate bitcoind that pulls the blockchain from the first instance (by adding it as its sole network connection using addnode) and periodically stop that then rsync out any changes? Or is there a less circuitous way of getting a coherent blockchain backup from a live bitcoind?
The easiest way would be doing a snapshot, but this method depends mainly on OS or Hardware support.

Another option is creating a bootstrap.dat file, which is basically a concatenation of all blocks in a single file. When the node finds this file in its data dir it loads all blocks from it before connecting to the network, so the initial load can be much faster (again, depending highly on your IO and processing capacity...).

You can create a bootstrap.dat file using the tools here. To restore, see https://bitcointalk.org/index.php?topic=145386.0