Speed of the FW 800 HD

Question

Hi !
How big is the difference between external HD (FW800) if RPM is 5400 or 7200.
If the machine is PowerBook G4 1.25 GHz, does it make any difference if the RPM of the HD is 5400 or 7200?
If it is portable HD which takes the power for the device from the firewire port, does it make difference if RPM is lower or higher?

Answer 1

<syriana voice> It's complicated</syriana voice>
From a practical standpoint, how a drive will work for you depends on the codec of the material you are editing and the number of streams you need to run simultaneously.
For example, DV runs at ~3.6MB/s, an absurdly low data rate. I used to capture DV material on my old Powerbook G4's internal 5400rpm drive when I had a Canon camera that wouldn't work with any other device on the same bus. I could go ahead and do a simple cuts only 1 stream edit with just the system drive. If I hooked up my 5400 rpm G-tech fw 400 mini, I could run a couple of streams while editing on the go. All very neat and no 7200 rpm drives in sight.
There are really five things you need to weigh when purchasing drives -
A. the connection protocol. A drive connected through FW400 will have a considerably lower throughput than the same drive connected through the system bus. If you are looking for the best bang for the buck, internal drives are the best way to go. In descending order of connection speed, I rank connection speed this way: Internal, esata, fw800, fw400. Note, I don't include usb2 as a viable protocol as they are not isochronous - that is they can not control the bus and send an uninterrupted data stream.
B. the drive cache. Drives with larger caches can load data in such a way that the pipeline never goes empty. This sometimes is more meaningful when you read/write lots of smaller files.
C. the rotational speed. The faster the disk rotation, the more rapidly the sectors come back under the read head. This doesn't necessarily translate into more throughput unless the drive sector system and read heads have been optimized for each other.
D. data distribution optimization. Most drives slow as they fill. External drives that are designed for A/V work slow less dramatically than drives designed as general backup devices.
E. RAID devices. Given you are distributing the Read/Write efforts over 2 or more drives, the speed of the individual drive becomes somewhat less important.
Have fun.
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