During routine pro-active checks last night, it was bought to my attention that a hard drive in one of our database servers was showing a warning error condition. The hard drive has been replaced and the data copied back to it. (The drives are RAID redundant so a failed drive does not take out a server, and we have multiple servers handling the same tasks).
This operation was completed by 0852 GMT. During this time, the site continued to operate correctly, there was no downtime or loss of performance.