The customer's data that was lost was, at the time, being hosted in Microsoft's data centers. Some media reports have suggested that Microsoft hired Hitachi to perform an upgrade to its storage area network (SAN), when something went wrong, resulting in data destruction. Microsoft did not have an active backup of the data and it had to be restored from a month-old copy of the server data, totalling 800GB in size, from offsite backup tapes. The entire restoration of data took over 2 months for customer data and full functionality to be restored.