Guinness holds over 20,000 online personnel records from the 1880s up through the time  when a pension ceased in the late 1990s or early 2000s. That accounts for about 80% of all employees who worked at Guinness during this period. The files contain birthdates, spouse's names, dates of employment, and dates of death. Since jobs were often passed from generation to generation, this source could be a jackpot for family history research.

Online search begins at the "Genealogy" tab on their website: http://www.guinness-storehouse.com/en/GenealogySearch.aspx. Grenham reports today in his blog that additional personnel records dating back to the 1850s and 1860s may also be available if you visit the Guinness archive in Dublin. Medical, financial and other personal details about your ancestor may be in the paper files.