We have been experiencing some relatively large I/O (IOPS) spikes on the SAN that supports our production SQL Server.
The spikes seem to fall at an exact time after the hour, each hour. We have investigated every known scheduled task source (SQL Agent, backups, scheduled SSRS Reports, etc.) and can't find any rhyme or reason to it so far.
We have use Activity Monitor as well, but it has not yielded any answers to date.
How would one go about definitively finding the source of I/O spikes? Are there monitoring tools (commercial or otherwise) that would help pinpoint the problem?