Storage controllers are usually rack-mount servers consuming around 200W each.
Typical mid-range storage array has two controllers but some arrays can have even more controllers. Below storage controllers are disk enclosures. Disk Enclosures typically consumes 150-200W. Disk enclosures are populated with disks. Below are typical power consumptions of modern disks.
|300GB 15K SFF HDD||6.2W||8W|
|450GB 10K SFF HDD||3.7W||6.3W|
|600GB 10K SFF HDD||4.1W||6.3W|
|900GB 10K SFF HDD||4.8W||6.3W|
|1TB 7.2K SFF HDD||2.95W||3.84W|
|2TB 7.2K LFF HDD||7.5W||10.6W|
|3TB 7.2K LFF HDD||8.5W||11.8W|
|100GB SFF SLC SSD||1.4W||3.9W|
|200GB SFF SLC SSD||1.4W||3.9W|
|400GB SFF MLC SSD||2.2W||3.7W|
SFF = Small Form Factor; 2.5"
LFF = Large Form Factor; 3.5"
So here is example calculation for Storage Array HP 3PAR 7400 having two storage controllers and seven disk enclosures.
Storage Controllers = 2x 200W
Disk Enclosures = 7x 150W
And following disks: 8x 400GB MLC SSD, 128x 300GB 15K and 40x 900GB 10K = 8 x 3.7W + 128 x 8W + 40 x 6.3W = 29.6 + 1024 + 252 = 1,305.6W
Total power consumption of such storage system configuration is 2,755W = 2.76 kW.