Disk Writes/sec and Disk transfer/sec eq zero, for about 6 seconds every 10-15 minutes

 Hi,

The problem I have is on a HP DL 380p Gen8, Microsoft SQL database server with Windows 2012R2. The SmartArray controller P420i has the latest 7.02 firmware, Caching enabled, battery ok, Physical Drive Write Cache  enabled. I tried also to disable write cache, and also 100% Write for controller cache.  

Every 10-15 minutes I have Disk Writes/sec eq zero for about 6 seconds. During this time, the counters Disk transfer/sec is also zero and the Current Disk Queue Length counter increases. This is valid for all 3 Logical Drives from the server (two raid1+0 and one raid1).

Please help, any ideeas?

Thanks,

Adrian