The More Firewire Drives The Better?
bewildering number of options make choosing dedicated storage for media
files seem like a tough question. For a facility that needs a massive
RAID system or storage area network to be shared by several
workstations, it is. But for a producer or editor who just needs
support for common SD and compressed HD formats on a single
workstation, it isn’t. Once you know your throughput, capacity and
redundancy needs, your choices become clear. Well, clearer.
to tape (or card or optical disc), but by the highest-bandwidth format
you regularly load onto your hard drives for general editing. If you
shoot and edit DV, then you’re looking at 3.7 MB/sec. But if you
transcode from HDV to DVCPRO HD, for example, base your calculations on
the 14.8 MB/sec required for DVCPRO HD. For HDCAM, calculate based on
whatever intermediate codec you use. Avid DNxHD, CineForm,
uncompressed, 4:1 MJPEG and other options are all intermediate codecs,
average throughputs from 18 to 35 Mbps, but the throughput demand
varies with the mix of I, B and P frames. So add a little padding to
your data-rate needs for these formats.]
by four. That will support reading and writing of a couple of video
streams, a few channels of audio (actualities, VO, music), plus a
graphics stream and overhead. Motion-graphics designers working with
uncompressed or lightly compressed material may not be able to find a
system that offers four times their format’s data rate. But if they can
live with, or at least tolerate, non-real-time performance, there are
still affordable options.
that at a facility other than your own (have you seen the price of HD
scopes?), this approach may work for you.
as megabits per second (Mbps). Drive transfer rates are typically
described in megabytes per second (MBps). Converting between the two is
simple: Eight megabits equal one megabyte. The chart, on page 35,
suggests that if you mainly edit in DV, a storage system that can
sustain 15 MBps will do. If you edit DVCPRO HD, 60 MBps will keep you
happy. Different intermediate codecs have different data-rate needs,
but 120 MBps will keep a few streams of most formats humming along.
rate, the amount of material required for a typical project and the
number of projects that will simultaneously be on the device.
typical source-to-final ratios. This isn’t the same as a shooting
ratio. I reduce the effects of location imagorrhea
with logging to trim down what ends up on hard drives.
footage, graphics, render files and so on. For a documentary, the ratio
may increase to 10:1 or 20:1. A motion graphic designer may have a
higher source-to-final ratio than a documentary or corporate editor,
but will also be working on shorter projects. So let’s call it a wash.
only five gigabytes, a one-hour documentary edited in DVCPRO HD could
require over a terabyte.
corporate jobs and one to three documentaries or short dramas. There’s
the job I’m finishing, the job I’m working on and the job I’m sitting
on while the client (and for the docs, that’s usually me) figures out
what the heck they’re going to do. My corporate work is mostly standard
definition (though that’s changing); the docs vary from DV to HDCAM
originals with editing taking place in some format that consumes less
than 75 GB per hour.
in fact, each of my two main workstations (one Mac and one Windows) has
a terabyte of main drive space for media files.
general ascending order of performance are FireWire 400 (i.e., standard
FireWire as found on DV cameras), FireWire 800, SATA, UltraSCSI and
Fibre Channel. I’m mixing technologies here. Typical "FireWire" drives
have either IDE or SATA mechanisms inside. Similarly, there are arrays
built around IDE drives, but with SCSI interfaces to the computer. But
most users group drives based on the type of cable they plug into the
slow on the track. Even with the recent Oxford Semiconductor 924
interface and a modern 500 GB SATA II drive, the best read performance
I’ve seen with FireWire 400 was just over 30 MBps. That’s good for over
four streams of DV and four of DVCPRO50, but not fast enough for
reliable and efficient use with most other formats. I’ve seen Firewire
400 drives alternately play back HDV footage without a problem, but
then drop HDV frames. However, I’ve always been able to reliably play
back the same HDV footage on an internal SATA drive I’d investigate
further if there weren’t better alternatives. But there are. For
example, an external drive built around the Oxford 924 can offer
FireWire 400 and 800, USB 2.0 and SATA ports. A single drive can give
you good performance at home and great compatibility on the road.
is viable with more formats, as long as you have an independent
FireWire bus that isn’t also supporting a VTR or camera. On most
computers all FireWire ports use a single bus, and occasionally a
camera’s or VTR’s FireWire signal will conflict with that of a FireWire
drive. You can avoid the conflicts by installing a second FireWire bus
through a PCI card in your desktop or a PC card or Express card in your
to SATA. Big moderate-priced drives can sustain around 70 MBps, and you
can combine drives for faster performance. You can get SATA cards for
desktop and laptops. For my needs, SATA is the way to go. At least for
this year. I don’t have anything against FireWire 400 drives. I have
six right here. While I don’t use them for main online storage, I use
them for backup, some location work and shipping media to collaborators.
up as a RAID 0, with files spread evenly across the drives, gives great
performance at a low cost. For example, a single SATA drive that can
transfer around 65 MBps (and that slows down as it gets full) could be
matched with three similar drives into a RAID 0 array and transfer over
|Video Format||MBps||(MBps) x 4||GB/hr||Hours/Terabyte|
|Estimate the speed and size you need in a storage system by finding the highest-bandwidth format you edit, multiplying by the number of streams you want to move at the same time, and estimating the amount of material you will have on the system at any one time.|
|DV (DV25, DVCAM) 60i||3.7||14.8||13||75|
|Uncompressed 10-bit SD 60i||27||108||97||10|
|HDV (25 Mbps) 60i||3.7||14.8||13||75|
|XDCAM (35 Mbps) 60i||5.2||21||19||53|
|DVCPRO HD 720/60i||14.8||60||60||17|
|DVCPRO HD 729/24pn||6.7||27||24||41|
|Avid DNxHD 220||27.5||110||100||10|
|CineForm 1080p24 or 720p60||19.2||77||70||14|
|Uncompressed HD 720p 8-bit||110||440||396||2.5|
|Uncompressed HD 720p 10-bit||138||552||497||2|
|Uncompressed HD 1080i 8-bit||120||480||432||2.25|
|Uncompressed HD 1080i 10-bit||155||620||558||1.8|
|Uncompressed HD 1080p 10-bit (4:4:4 RGB 24fps)||190||760||667||1.5|
of them is lost. RAID levels 3, 5 and 6 add data security and
redundancy by adding increasingly secure parity information needed to
recreate files across drives. With RAID 6, you can theoretically have
two drives fail and still not lose data.
advantages. But overall, this data security often comes at the cost of
reduced throughput and storage capacity, and always comes at the cost
of increased, well, cost.
or 5 system appropriate for video work can easily cost $4,000 to $7,000
or more. If you run a full-time facility with multiple seats and
multiple editors, then a higher-level RAID system or storage area
network is a good economic choice. Lost time is lots of lost money.
regularly back up the data on each to FireWire drives. It’s not a
perfect solution and I plan to buy a higher-end RAID system in 2007,
but for now it works.
knowing the best mechanism of yesteryear doesn’t mean I know the best
choices today. Western Digital and Maxtor used to be on my do-not-fly
list. Now some people have great experiences with them.
other hobbies, so these days I buy from video-savvy vendors. It saves
time, doesn’t cost much extra and gives me a direct line to tech
support and replacement parts if things go wrong (which they haven’t,
knock on wood).
Video pros work their drives harder than consumer and business users
do, and our systems, therefore, generate more heat. So even if the guy
at the megastore says you can stick four more hard drives into your
computer, or says he edits video with the FireWire drive that’s on sale
today, you might not get what you need.
drive just went kaput. It often turns out they bought a consumer
FireWire drive that didn’t have an internal fan or heat sink adequate
to keep cool a constantly working drive. And I’ve seen similar problems
with some RAID systems built into computer cases.
internal RAIDs. The difference is intelligent heat dissipation, and I
find that intelligence most reliably with vendors and resellers who
really understand the needs of video professionals.
terms, around $1,000 per terabyte for single drives and SATA RAID 0,
around $3,000 per terabyte for multi-terabyte Fibre Channel systems.
Compared to the guy in 1997 who rented out 9 GB hard drives for $125
per week, hard drive storage today is a bargain.
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