LaCie FIREWIRE 800/400 user manual Available Storage Capacity, Optimizing Data Transfers

LaCie Biggest Quadra	Technical Information
User Manual	page 45

7.2. Available Storage Capacity

A gigabyte (GB) means 1,000,000,000 bytes. In or- der to utilize a hard disk drive, it has to be formatted first. Formatting a disk consists of the following: the operating system erases all of the bookkeeping infor- mation on the disk, tests the disk to make sure that all of the sectors are reliable, marks bad sectors (i.e., those that are scratched) and creates internal address tables that it later uses to locate information. Once formatted, the actual available storage capacity varies, depending on operating environment, and is generally about 5 to 10% less than the non-formatted capacity.

Technical note: Capacity depends on RAID mode selected:

❖RAID 0: 100%

❖RAID 0+1: 50%

❖RAID 5: 75%

❖RAID 5+spare: 50%

7.3. Optimizing Data Transfers

Data transfers are the flow of data that accomplish- es a task, usually related to moving data from storage to computer RAM, or between storage devices. With external drives, such as the LaCie Biggest Quadra, the data is transferred from the drive to the computer via the FireWire or USB interface. The data is fed from the drive through the FireWire port on the drive, and passes to the computer through the FireWire host-bus adapter interface.

Computer manufacturer’s implementation of the FireWire host-bus adapter interfaces vary widely. For computers running Windows 2000 and later, the FireWire interface, which is referred to as either IEEE 1394 or iLink on PCs, is less common as a native host- bus adapter. Nearly all recent Apple computers have na- tive FireWire interface ports.

The FireWire interfaces specify certain require- ments, filed under the OHCI (Open Host Controller Interface) standards. All LaCie drives comply to OHCI standards and have been rigorously tested on computers that have host bus adapters that also comply to OHCI

standards. Unfortunately, not all manufacturers respect these guidelines, and anomalies may arise with comput- ers that have host bus adapters that do not conform to OHCI standards.

For the best performance, connect your LaCie Big- gest Quadra directly to a native FireWire port on your computer, and avoid daisy-chaining. During data trans- fers, it’s best to wait before launching other applications that will be using the same port.

If you do not have a native FireWire port, LaCie offers FireWire host bust adapter cards, also known as PCI or PC/PCMCIA cards, that have been tested and comply with LaCie drives. Please contact your reseller or LaCie Customer Support for more information.

Technical note: Another important factor in file transfer speeds is how the drive has been for- matted. For more TN information in choosing the correct file system format, please see section 7.1. File System Formats.