Doing an fsync per-record when receiving the complete HDB is a performance
disaster. Among other things, if the HDB is very large, then one slave
receving a full HDB can cause other slaves to timeout and, if HDB write
activity is high enough to cause iprop log truncation, then also need full
syncs, which leads to a cycle of full syncs for all slaves until HDB write
activity drops.
Allowing the iprop log to be larger helps, but improving receive_everything()
performance helps even more.
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