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Reliability Of Hard Drives; Innovative Video-related Products

Cutting Edge By Dave Shapton
Published May 2003

While hard drives have become the de facto data storage medium in the studio, tape is often still used for outside work, occasionally alongside a hard disk system as backup. This month, we look at the reliability of hard drives and investigate some innovative video-related products from Sony, which could soon be commonplace in the audio world.

I've just spent an amazing week helping Sony Broadcast & Professional Europe demonstrate its new DSR DU1 video hard disk recorder, a compact self-contained unit offering three hours of video recording time, which either slots into the back of a big professional camcorder, or into a belt-pack for use with smaller camcorders. My personal favorite in this latter category is the DSR PD150, which is a kind of 'professionalised' version of a domestic camcorder, featuring dual balanced mic inputs with individual level controls. And since DV-format audio works at a 16-bit resolution and 48kHz sampling rate, if push came to shove, you could actually use this camcorder for location audio recording with fairly decent results.

Sony's DSR PD150 camcorder features dual balanced mic inputs with individual level controls and can record at a 16-bit/48kHz resolution and sampling rate, making it useful for recording high-quality audio, in addition to high-quality video.Sony's DSR PD150 camcorder features dual balanced mic inputs with individual level controls and can record at a 16-bit/48kHz resolution and sampling rate, making it useful for recording high-quality audio, in addition to high-quality video.Camcorders like the PD150 give a picture quality that's staggering compared to VHS or S-VHS, although it's debatable whether this could be considered 'broadcast quality' since the BBC or Channel 4 almost certainly wouldn't accept what's acceptable to a local cable channel for on-air use. However, if you're interested in video effects or making music videos, you could certainly use a camcorder like the PD150 and process the video through the dozens of plug-ins available with video editing programs like Premiere, Edition or Xpress DV — not forgetting Final Cut Pro on the Mac. Alternatively, you could simply make sure that you shoot in optimum conditions to make the most of the camera's abilities.

I've bought a PD150 for my own use, and I'm going to use it with a DU1 on a project I've wanted to do for ages: a short film about the city of Bradford that I'm going to shoot, edit, write and perform the music for, and burn to DVD. It's a 10-minute film that will probably take me two years to produce, and, in a sense, I'm only doing it because I can. And the reason I can is because the equipment I need to get a good result is affordable — 10 years ago it would probably have cost somewhere between a hundred thousand and a million pounds.

The Germane Issue

You might be forgiven for thinking you're accidentally reading Video On Video at this point, but the reason I wanted to mention the DU1 is because it really shows that hard disk recording has reached a point where it's good enough to replace tape. Of course, I'm not talking about audio or video quality here, because digital data is pretty much independent of the medium used for the actual storage; the important thing is that hard disks can now be made tough and reliable enough to trust with vital audio and video data — even on the move. And it's not just a matter of putting them into tougher cases — somehow, hard drives just don't seem as fragile as they used to.

Such increased reliability is an even more remarkable achievement when you consider that every time the capacity of a hard disk increases, so does the mechanical and electrical precision needed to pack and retrieve the data from smaller spaces. A few years ago, someone explained to me that if you scale up the movement and position of a hard disk's read/write head, it would be equivalent to flying a jumbo jet one foot above the ground. And when the next generation of disks comes out, this equivalent distance will be reduced to a millimetre (to mix imperial and metric measurements for a moment).

Now, I'd better stress that I'm not saying you no longer need to be careful with hard disks: with the type of disk you get in desktop computers, it's still better to avoid moving them when they're spinning — especially when they're reading or writing. Most disks these days can withstand a 30G shock when switched off (which is roughly equivalent to a 10cm drop onto a hard surface), but will suffer badly if they're subjected to even a fraction of that abuse while in operation. Nevertheless, I've seen people treat their laptop computers pretty roughly while they're turned on and have rarely seen any problems as a result.

The Sony DSR DU1 hard disk recorder is a durable portable device capable of storing up to three hours of video.The Sony DSR DU1 hard disk recorder is a durable portable device capable of storing up to three hours of video.

What Sony have done with the DU1 hard disk recorder is to use a notebook-type drive and give it extra protection. We handled five DU1s very roughly for a week and experienced no mechanical or electrical problems at all. We even took them underwater (admittedly, in an underwater housing) and have speculated that this could have been the first time hard disks have been used to record video beneath the waves.

Size Vs. Reliability

So the question is, are we at the point in the evolution of recording where we can confidently dispense with tapes altogether? It's not a new question, of course, and I've discussed the subject in Cutting Edge before — after all, we've been able to record multitrack CD-quality audio on PCs for at least a decade. But the biggest change when comparing tape and hard disk now is the price of storage: 12 years ago, a Gigabyte of hard disk capacity cost around a thousand pounds — these days, it costs less than a pound!

Hard disks are incredibly reliable, but they're not, as some people think, as incredibly reliable as they were a couple of years ago; and the fact that several manufacturers have reined in their warranty periods is perhaps a reflection of this. Nevertheless, when you consider the sort of thrashing a hard disk has to go through when working with digital media, you simply have to wonder at the technology. The fact is that error correction is now so robust, it's unlikely that anything short of a catastrophe will damage your data.

Comparing this with tape — which can be described as a contact medium — tapes wear out, and they stretch and twist. Nasty — although not as nasty as when a hard disk goes down! But this is the difference between linear and non-linear media: when a tape fails, the failure is local and the rest of the data is still there on another part of the tape. In contrast, when a hard drive goes down, for whatever reason, normally you'll lose everything.

However, because hard disks really are quite affordable these days, for very little outlay we can probably have more storage than we need. As an example, for a little under £250 I've just bought an external 250GB drive with USB1, USB2 and Firewire (IEEE1394, or iLink) connectivity — and note that this isn't just the raw drive, it's a nicely packaged external unit complete with Firewire and USB cables. Like most people working in media-related industries, I'm starting to use this type of storage by default because it's incredibly flexible and, with Firewire or USB2, it's fast enough for most applications.

Two hundred and fifty Gigabytes is a veritable cavern of storage capacity and, from the consumer's perspective, I had to think very hard to find a way I could fill it up. If we think in terms of audio CDs, though, the average CD has around 650MB of data on it, which means you can fit around 380 CDs on a single 250GB drive — more than most people have in their collection. So for less than the price of a 10GB iPod, you can store your entire CD library, uncompressed. Admittedly, this isn't a portable solution, and you'll still need a computer to play the files, but that's not a problem for most people since they listen to music in their living room or bedroom anyway.

Good News & Bad News

So the fact that high-capacity hard drives are now affordable is good news. Unfortunately, the bad news is that hard disks, while reliable most of the time, can still fail; and even though you'll undoubtedly have your entire CD collection sitting on a shelf somewhere if your hard drive-hosted collection takes a dive, you're not going to want to spend another three weeks digitising them again. But there's an obvious solution: use two disks and put the same data on both. If one of them fails, you still have all your data and have an opportunity to install another backup disk.

This technique is called 'mirroring' and is one of the many automatic facilities afforded by using a RAID (Redundant Arrays of Independent Disks) system for data storage. Now that hard disks are so cheap, it really does make sense to mirror any drive that has important data on it, and there are virtually no penalties for doing this. In a RAID system, data is presented to the two disks simultaneously, so there's no loss of speed, and when a drive fails you can just carry on working.

What I'd really like to see from the drive manufacturers is the option to trade capacity for reliability. I reckon the easiest way to do this would be to incorporate two independent disk drives within a single unit — either internal to the computer or external. The two drives would be mirrored locally, so that they wouldn't take up two ports on a drive controller. In fact, they'd behave exactly like an ordinary drive, except that your data would be twice as safe!

It's A Tough Job, But...

While working with the new Sony DU1 hard disk recorder, our task for the week was to produce a video documentary for each day of the Dubai National Topper Championship, a sailing competition for young aspiring sailors. Music was an important part of the project, although, as is often the case, there wasn't actually budget for it! So I took the one track that had been written, sliced it up and remixed it for each day's film using Sonic Foundry's Acid.

To keep out of the way of the camera operators and editors, I took the precaution of working beside the swimming pool, where I had a laptop connected to the video editor's network via a wireless link. When I had finished each day's mix, I rendered it to a WAV file at 48kHz and copied it to the editors' central storage, giving them instant access to the content for use in their video timelines.

Published May 2003