Thoughts on Selecting a FireWire or SATA Hard Drive

[ This article was first published in the January 2007 issue of
Larry’s Final Cut Pro Newsletter. Click here to subscribe. ]

One of the questions I get asked in every class is what kind of hard drive a student should buy. For years, the answer has been FireWire, but, now, things are a bit more complex. So, I want to use this article to explain why.

FireWire has long been a staple of the video editor – however, there is an inherent limitation with FireWire which makes it worthwhile to consider other interfaces as you add more gear to your system.

During my recent seminar tour, I was traveling with both a SATA hard drive and a FireWire hard drive because I wanted to illustrate the differences between the two protocols.

Here are my basic conclusions:

1. Since the two drives cost about the same, if you want the best portability, choose FireWire. If you want the best performance, choose SATA.
2. If you are using a single FireWire drive, there is no essential difference between connecting it via FireWire 400 or FireWire 800.

Some Background

Firewire and SATA are both communications protocols used to move data between computers and hard disks. Over the years, we have had a lot of different protocols — SCSI, serial, parallel, and, more recently, Fibre Channel.

The more efficient the protocol, the faster you can get data to and from the hard disk.

FireWire has been available for the Mac for years and has become the format of choice for video editors because the FireWire protocol efficiently delivers the huge files required.

As a side note, even though USB-2 is supposed to provide even greater bandwidth, don’t use it for video editing on a Mac. It won’t work and you will constantly get dropped frames.

However, FireWire has three significant problems:

1. There are no native FireWire drives — instead, all data is translated between the hard disk and the computer using a “bridge” chip.
2. FireWire is a very “chatty” protocol — drives spend a lot of time talking to the computer and each other.
3. Firewire is a bus — the speed of your FireWire devices is often determined by the slowest FireWire device connected to your computer; most generally, the camera or video deck.

In comparison to the overall hard disk market, the market for FireWire drives is tiny. So small, in fact, that there are no native FireWire drives. Instead, manufacturers combine an IDE (or EIDE) hard drive with a bridge chip to translate between the native language of the drive and the FireWire protocol the computer expects. (There is, of course, other stuff in a hard drive, like power supplies, cases and connectors, but for the purpose of this example, the hard drive and the bridge chip are what we will focus on.)

This means that the speed of your hard drive is limited, or gated, by the performance of the bridge chip.

There are a variety of bridge chip manufacturers, however, for video there is only one company to consider: Oxford Semiconductor. They make a variety of bridge chips, the 911 and 922 were earlier efforts and the 924 is their current chip, that handle the translation between the hard drive and the computer.

The problem is that even the best bridge chips take a toll on data rates to and from the hard disk. For DV video this is not, generally, a problem. However, as you start to work with the multiple video streams of a multiclip or move to higher quality formats such as DVCProHD, the data rate of your hard drive becomes significant.

Here’s a short table of some common video data rates:

Common Video Data Rates

Video Format	Data Rate
DV & HDV	3.75 MB/second
DVCPro-50	7.5 MB/second
DVCProHD	15 MB/ second
Beta SP (Uncompressed 8-bit)	20.2 MB/second
DigiBeta (Uncompressed 10-bit)	26.7 MB/second
1080i HD (Uncompressed 10-bit)	~150 MB/second

Another problem with FireWire is that the computer and hard drive spend a lot of time talking to each other in the background, making sure they are still connected and exchanging other pleasantries which have nothing to do with your data. With one or two hard drives, this isn’t a problem. However, I have seen significant speed slowdowns with as few as five hard drives attached to a G-5.

In other words, the more FireWire drives you add to your system, the more things will slow down. For this reason, I recommend that you are better off buying a RAID if you need more storage, and not just add more and more FireWire drives to your system.

NOTE: By the way, if terms like RAID 0 or RAID 1 confuse you, read this short explanation of how RAIDS are defined.

For me, the practical limit of FireWire drives connected to a G-5 computer is five. Final Cut will support up to 12 drives used as scratch disks.

FireWire Speed Tests

To illustrate what I’m saying about FireWire speed, I recently compared the speed between the ports of a G-Tech FireWire drive which had both FireWire 400 and FireWire 800.

First, let me say that this G-Tech drive has been schlepped all over the world during the last year — well over 75 plane flights all over the US, Canada, and Australia. I have never seen a more rugged, or quieter, drive.

Here are the results:

The image on the left measures the speed of a hard drive connected using FireWire 400, on the right is the same drive on the same computer connected using FireWire 800. The only difference between these two tests was how I connected the hard drive to the computer. The tests were run about five minutes apart and the drive was about 60% empty. (The key numbers to look at are for “Combined,” and, yes, in this example, FireWire 800 is slower.)

There are several factors that determine the speed of a hard drive:

• All hard drives access data faster or slower, depending upon where the data is located on the hard drive (Inner is faster).
• Hard drives generally write (record) data faster than they read (play) it.
• The fuller a hard drive, the slower it goes.

Notice that in this example FireWire 400 writes faster than FireWire 800 and that the read speed is identical. Why? Because the speed of your FireWire hard disk is dependent more on the speed of the bridge chip than it is on the how the drive is connected to your computer.

Getting to Know SATA

SATA is a new protocol that rose to prominence with the release of the G-5, because SATA is the default hard disk protocol for the G-5 and all Mac/Intel systems.

The good news is that SATA is fast, very fast. The bad news is that SATA requires a PCI card for your laptop or tower; and because it needs a card, it won’t work on a MacBook or iMac, neither of which have a slot to install the card.

Many hard drive manufacturers are selling SATA drives. Maxtor makes an internal drive for the MacPro, G-Tech, LaCie, CalDigit, OWC and others make external drives. (See the story on my testing of a CalDigit system.)

PCI cards are available for both MacBook Pro and MacPro systems from Sonnet, ProMax, LaCie, and others. However, be careful. I recently purchased a SATA hard drive from LaCie which uses a SATA connector that only works with a LaCie PCI card. This prevents me from moving this hard drive to any other computer, because the used cable to connect it is non-standard. You are much better off buying the card from Sonnet and a hard drive from a vendor that supports the standard SATA plug to prevent getting locked into a proprietary cabling system.

SATA Speed Test

Let’s compare the speed of the SATA drive to the FireWire drive.

Important note: These stats compare two different drives, which are not exactly comparable. Your numbers will vary, though SATA will always be faster.

In this example, the SATA drive is on the left, FireWire 800 is on the right. When we look at the Combined results, the SATA drive is 2.3 TIMES faster than the FireWire drive. This is a significant performance boost.

Note: These tests used a MacBook Pro Core 2 Duo. If I ran the sames tests on a MacPro, the FireWire numbers would be essentially the same and the SATA numbers would be closer to 150 MB/second in Combined throughput. G-5’s would be slightly slower.

Conclusion

On my system, I have a SATA drive, a two-drive RAID actually, that I use as my scratch disk for all my editing. Then, I have a second, FireWire, drive that I use to move files from one computer to the next.

As I said at the beginning, if portability is your prime concern, FireWire is the best choice. However, if performance is more important, and you don’t need to move drives from one computer to the next, my strong recommendation is SATA.

Update – 12/29/06

Long-time reader, Andreas Kiel wanted to clarify something I wrote:

[The problem with FireWire speeds is] Apple’s implementation of the FireWire bus structure.

 

Unibrain for example had a product for TCP/IP over FireWire which especially did shine with heavy loads and outperformed 1G Ethernet with a FW400 connection, since FW isn’t chatty. Also in surveillance FW is loved since you can put a real lot of cameras to the bus without slowing down the speed.

 

With third party FW800 cards in a desktop machine you get a way better performance than with the integrated ports. I haven’t tried portables.

Larry replies: Andreas, thanks for this additional information.

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