The real IOPS for exadata

From the graph you can see, the HC and HP IOPS are calculated separately. To illustrate the problem a simple presentation of the form:

Exadata Rack	Disk Type	Disk Count	Disk Model	IOPS
FULL (1/1)	HP	14 * 12 = 168	15000rpm SAS 600G	50000
	HC		7200rpm SAS 3T	28000
HALF (1/2)	HP	7 * 12 = 68	15000rpm SAS 600G	25000
	HC		7200rpm SAS 3T	14000
QUAR (1/4)	HP	3 * 12 = 36	15000rpm SAS 600G	10800
	HC		7200rpm SAS 3T	6000

A simple look can spot patterns: the total IOPS given in the datasheet is actually superimposed.

A quarter rack in ( HC - high capacity ) has only 6000 IOPS

Exadata use hard disk provider and models are as follows, the reader can google the detailed parameters: (Note 2T disk has been discontinued)

600G 1500rpm HP disk: Seagate ST3600057SS, Hitachi HUS156060VLS600
3T 7200rpm HC disk: Seagate ST33000650SS
2T 7200rpm HC disk: Seagate ST32000444SS, Hitachi HUS723020ALS640

Also, exadata's performance is affected by temperature (http://www.dbaleet.org/exadata_how_to_caculate_iops) :

Actually a test disk I / O performance when installed in Exadata steps in Step 9 - INFO: Step 9 RunCalibrate. This step will Exadata Cell disk IOPS and MBPS test. If the hard disk IOPS less than the requirements established in the time of installation will be an error. For example, there is a very common situation: Seagate hard at room temperature below 20 degrees Celsius, IOPS will become poor. See Bug 9,476,044: CALIBRATE IOPS SUBSTANDARD. This problem is a "feature" of the Seagate (Seagate) SAS disk later the Exadata to use the Hitachi (Hitachi) did not find this problem. The Exadata hard disk suppliers on only two, in view of this, in general we do not recommend the computer room air conditioning alignment Exadata blowing heat.