Only limited disk storage capacity is needed, because only a limited number of online courses will be available in the first phase.

只需要有限的磁盘存储空间，因为第一阶段只有有限的在线课程。

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While storage capacity demand continues to grow at over 50%, year over year, the storage capacity growth in hard disk drives has been slowing down from what it was in prior years.

FORBES: Changing Digital Storage Requirements for Clouds and Mobile Devices

Hard disk drives provide high capacity cost effective digital storage and thus we think that the decline in HDD shipments in 2012 will likely not continue.

FORBES: Why We Should Expect HDD Growth Later this Year

For a number of reasons the total storage capacity for a 5, 400 RPM disk can be higher than a 7, 200 RPM disk.

FORBES: Seagate Discontinuing 7,200 RPM Drives--A Focus on Capacity?