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How You Connect Your Drive Determines Its Speed
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.
NOTES
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.
Larry Jordan is a post-production consultant and an Apple-Certified Trainer in Digital Media with over 25 years experience as producer, director and editor with network, local and corporate credits. Based in Los Angeles, he's a member of both the Directors Guild of America and the Producers Guild of America.
The information in this article is believed to be accurate at the time of publication. However, the author assumes no liability in case things go wrong. Please use your best judgment in applying these suggestions.
The opinions expressed in this article are solely those of the author. This newsletter has not been reviewed or sanctioned by Apple or any other third party. All trademarks are the property of their respective owners and are mentioned here for editorial purposes only.
Links to my website home page or this article are welcome and don't require prior permission.
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