How You Connect Your Drive Determines Its Speed

Posted on by Larry

[ This article was first published in the March, 2010, issue of
Larry’s Final Cut Pro Newsletter. Click here to subscribe. ]

In the past we obsessed about the rotational speed of a hard disk, how much cache it had, or even the controller chip it used. While these are important, they pale in significance when compared to the impact of how you connect your drive to your computer.

A few days ago, I had a lengthy conversation with three folks at Ci Design, who make the iStoragePro product line about their family of hard disks and RAIDs. Zin, Cupid, and Katie Khor joined me for this discussion. (Thanks to Katie Khor for setting this meeting up!) Zin is their sales engineer, who did most of the explaining.

As a point of reference, CiDesign has over 27 years experience in storage design. Their latest product line is iStoragePro. According to Katie, they focus on creating a full-range of system solutions, offering the best in performance, with systems specifically designed for video and audio editing on the Mac.

We began our conversation talking about their FireWire drives. And, I must confess, that there’s a point where one FireWire drive looks a lot like everyone else’s drive – especially because they all use the same controller chip (Oxford) and same hard drive manufacturers (Hitachi, Seagate, Western Digital, Fujitsu). Differentiation is very hard in this industry.

However, our conversation veered into improving performance based upon how the drive is connected to your computer. And I found this much more interesting — and helpful. So I summarized our discussion in the bullet points below.

Two starting points to keep in mind:


1. A single hard drive connected inside a recent model MacPro transfers data between 75-80 MB/second. If you need faster speeds, you need to harness multiple hard drives together into a RAID.


2. Different video formats require different data transfer rates. For example, DV requires 3.75 MB/second. P2 requires about 15 MB/second. RED requires about 38 MB/second.




For a description of what RAID terms mean, click here.
For a description of data rates by video format, click here.

USB. Based on my tests, a single USB-connected drive transfers data between 10-15 MB/second. This puts it at the low-end of the speed equation. This protocol works great for slow devices like mice and keyboards, but is severely limiting for hard drives. I don’t recommend using any USB devices for video editing.

FireWire 400. Based on my tests, a single FireWire 400-connected drive transfers data between 20-25 MB/second. This is because all FireWire drives use a “bridge chip” to convert from the format the drive uses, such as EIDE, to the FireWire format. This conversion takes time. Plus, the size of the “transfer pipe” provided by FireWire 400 is small. FireWire 400 RAIDS can achieve speeds of up to 40 MB/second.

FireWire 800. Based on my tests, a single FireWire 800-connected drive transfers data between 45-55 MB/second. This is fast enough for many video formats, though not enough for extensive multiclip work. Also, when you connect both FireWire 400 and 800 devices to the same computer at the same time, the FireWire 800 devices slow down to nearly FireWire 400 speeds. This is true of all Macs. The only way around this is to install a separate FireWire 800 card in your computer. FireWire 800 RAIDS can achieve speeds of up to 90 MB/second.

eSATA. Based on my tests, a single eSATA-connected drives transfer data between 70-90 MB/second. However, eSATA requires an interface card to be plugged into your computer. Many laptops and all iMacs don’t support these cards. eSATA RAIDS can achieve speeds of up to 400 MB/second.

iSCSI. Based on my tests, iSCSI-connected drives transfer data up to a maximum speed of 100 MB/second (limited by the speed of your network switches). iSCSI is almost always used for multi-disk RAIDs, not single disks. iSCSI connects via an Ethernet cable, but requires a gigabit Ethernet connection to achieve these speeds. iSCSI also has the benefit of being able to connect thru a data switch, allowing the hard drive to be located in a different room.

FibreChannel. Based on what the iStoragePro engineers told me, 1 port FibreChannel transfers about 350 MB/second. 2 port FibreChannel supports transfers at about 700 MB/second. FibreChannel systems are always RAIDs, not single disks. The principle benefit to fiber, in addition to it’s high speed, is the distance you can get between the edit suite and the storage. This can be up to hundreds of meters.

Mini-SAS. Based on what the iStoragePro engineers told me, Mini-SAS-connected RAIDS (and this, too, is a RAID-only protocol) can transfer data between 600 – 700 MB/second. The best interface card to use is from ATTO. This speed is sufficient for all multiclip work, as well as editing 2k and 4k images.

SAS-Extended. Based on what the iStoragePro engineers told me, SAS-Extended-connected RAIDs can transfer data between 700 – 800 MB/second. This, too, is fast enough for all current video editing. SAS-Extended is a good protocol to use when one RAID is supporting multiple edit suites.

I found this information very helpful in picking the right system for connecting storage systems, based upon the video formats I want to be editing.

If you want to learn more about the full product line that iStoragePro offers, please visit here.

Also, for laptop owners, they offer two expansion chassis, which allow you to add cards and storage to your laptop. (Currently, the expansion chassis only supports Red Rocket, not AJA or Blackmagic Design cards.)

iStoragePro has some very cool stuff.

UPDATE — MARCH 23, 2009

Ben Balser writes:

Question, were you measuring “burst rate” or “sustained rate” for those drives?

Larry replies: Ben, the AJA tool reports average rate.


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