Data Storage Device: Compact Flash VS Hard Disk

In the embedded system a device for recording (storing) information is required.
In this device, the operative system (O.S) will be installed and additional data can be saved.
Two options:

2.5 Hard Disk Drive (HDD):

• Low cost (price GB/€)
• High power consumption
• Mechanical moving Parts
• Big size

Compact Flash memory card (CF):

Just the opposite from the Hard disk, that is to say, high cost per GB, low power consumption and size and non moving parts:

• Shock: Compact Flash cards have an operating shock rating of 2,000 Gs, which is equivalent to a 10-foot drop
• Data reliability: Compact Flash data is protected by built-in dynamic defect management and error correction technologies, but the
• Power: Typically consuming less than five percent of the power than that required to operate 1.8" and 2.5" disk drives, CF cards run at 3.3V or 5V with a single power supply.
  

For this project is more interesting to use a Compact Flash as data storage device (connected to the IDE bus throw a CF-IDE Adapter) , because maybe the embedded system will be used in a mobile robot and CF with non moving parts is more resistant to the shocks and make the system more autonomous with less power consumption.
In addition a 4GB memory is enough for install the operative system and other necessary software.

Sources:
CompactFlash.org