> At a coarse level, the symptoms sound afwully like scenarios in
> standard OS textbooks: simplistic seek optimization causes
> starvation.  The textbook approach is to do SCAN elevator sorts: once
> the disk arm starts a sweep, new requests are postponed until the
> next, reverse sweep.  Within a sweep, requests are serviced in-order.

And of course this is complicated by ordering constraints between
various writes, which I seldom see mentioned in this connection.  Such
constraints mean either deferring some requests until `later', cutting
a scan short, or doing something a good deal more complicated than the
simple scan algorithm outlined....

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