by young » Sun Nov 11, 2012 11:29 pm
You can actually choose. Depending on the reason for a node crash, you may find that one option or the other is better. For instance, if the problem was a bad disk, you may no longer have the data and will need to get a copy from the rest of the cluster. If the problem was a bad power supply, the data is still on disk and it is faster to read the data from disk than to transfer it from the other nodes.
If a node has been offline for a long time (more than a few hours), it is recommended not to read from disk. In this case, you should wipe the disk (using dd) before restarting the Aerospike server on the node.