Not sure about the word shard, but the 1401 used sharded storage in 1959:
https://en.m.wikipedia.org/wiki/IBM_1401
That was the best seller in history, at the time, but there are mechanical computers that played similar tricks going back to the early days of punch cards.
The Hollerith Tabulator won a competition in 1888.
https://www.census.gov/history/www/innovations/technology/th...
Anyway, yahoo probably sharded by the mid to late 1990s.