HDV and hard drive speed and RAIDs
 

hello everyone,

I'm still relatively new to this, and I have a question that seems very basic, but I can't find an answer searching google and these forums. First off, I'm working with a Mac Pro, 2.66 quad cores, 4gb of RAM. I currently have the included 250gb hard drive as my boot disk, and I have another 750gb drive for media files and working in Final Cut Studio 2. Until recently I have been working with a DVX100b camera, and this set up has worked just fine. Recently, I bought a Canon HV30, and now I want to start working with high def...

So... It's clear I'm going to need more hard drive space, but I'm puzzled about which direction I should go in order to deal with the 1440 x 1080 the Canon is capable of recording... add in 24p and 30p options on the camera, and the disk requirements seem to jump consderably. But here is the thing I'm puzzled about... The Canon is an HDV camera, which should imply that it maxes out at 25mb/second, which can be handled by any hard drive I put into my mac pro. But then I read about the requirements for editing 1440 at 24p and they seem to demand disk speeds much higher than that.

First off, am I reading that right? Is that even possible, when the initial recording is made at 25mb/s on the HDV tapes?

Second... if it's true that I need more speed for editing, will setting up a RAID with my two remaining drive bays do the job? I really don't have the money to invest in a hardware based RAID right now... my plan was to buy two 1TB Seagate drives and set them up as a Raid 1. I know that this won't help me with write speeds at all, but it gives me some insurance working with these files and it should help with read times, as I understand it. On the other hand, if I need to move to a RAID 0 to get the speed I need to edit 1440 @ 24p or 30p, then I'm fine with doing that.

The problem is, I can't find anywhere that says definitively, what the required speeds are for editing to the full potential of this camera. I can find various info on the sustained read and write speeds of all the various drive set-ups, but right now I have no idea what I need to get the most out of this camera.

So... am I crazy? Is it possible that somehow you need more speed to edit this video than the 25mb/s that it takes to capture it in the first place? If so.. just how much speed do I need, and can I get it with an internal software RAID, or do I have to start saving up for a hardware RAID and stick with lo fi until then... Also... if it matters, I'm doing almost nothing in terms of Motion and 3D, etc. I'm basically just cutting and doing fades on long takes of landscapes.. and occasionally speeding things up or slowing them down to create time lapses and slow motion. I don't do so much work that long render times bother me... all I care about is getting the best looking footage I can get out of this camera.

Thanks in advance for the help!

HDV & Hard Drives
 

Hey Stephen,
I had the same issue as you!
I just bought my New 8 Core Mac Pro and before I began called Apple and they helped me out allot. They even helped me on the phone step by step.

I added (2) Seagate 1TB Hard Drives to bays 2 & 3
http://www.bestbuy.com/site/olspage....=1186003683968

I only paid $189 for them and that was the cheapest I could find.

I went to Disk Utility and made both drives appear as one. I now have on my desktop my OEM Hard Drive and a second drive that is 2TB (1.83 after converting).

This gives me super fast speed - no drops outs - handles full 1080 HD like butter - I love it!!

Welcome to the forum, Stephen.

Actually there are tons of posts on this forum regarding this very issue, and I've posted a few "how-to" tricks on the issue myself but they've been spread across various forum topics.

There is one important factor to keep in mind when editing, regardless if it's SD or HD: It's not necessarily the bandwidth of the video codec you're working with that becomes the determining factor for how fast your HDD setup needs to be, but more how many *streams* of video you're working with in the timeline. More streams, more bandwidth.

Almost all systems today can easily handle a single (sometimes double) streams of HD in a FCP timeline without dropping frames. But, as soon as you add filters, effects and of course more streams the bandwidth requirements go up substantially.

A 2-drive RAID will handle 2-3 HD streams easily but if you get beyond that you'll run into playback issues.

Search our forums again for "RAID SETUP" and other RAID related posts and you'll run across more information than you'll have time to read.

Thanks Robert,

I think you hit the nail on the head when you said

"Search our forums again for "RAID SETUP" and other RAID related posts and you'll run across more information than you'll have time to read."

That, and similar searches were the first thing I did, and while I got a lot of useful information reading until 3am last night until my eyes were bleeding, nowhere did I see that simple bit of information you just handed over. I've read the sticky's at the tops of the pages and all the basic FAQ's but I didn't find anywhere that explained that basic rule of thumb.

Sounds like, even though the internal RAID is obviously not the optimal set up, in terms of what the Mac Pro's are capable of handling, if I'm not doing heavy effects or trying to blend more than two or three streams at a time, that should get me started without a problem. From the sound of it, I'm guessing that your reference to a 2 drive RAID is meaning RAID 0, like Johnnie is talking about in the post above. For security's sake, I'd prefer a RAID 1, but security doesn't do me any good if I can't do the work.

Thanks for the tip.

Johnnie:

Those disks are sold out at Best Buy now, I was confused as to whether they were the same as the Barracudas like this:

http://www.newegg.com/product/produc...82E16822148274

But it looks like it's just the difference between the retail and OEM versions. Given that even with tax, it's within about $5 of the best price I can find online, I think I'm going to run down the street and pick up a couple of them today. Thanks!

HDV in 1080 is a piddly 3.5 mbytes/sec

your bare SATA drive will do 60-80mbytes/sec

your 2 drive SATA array will do ( should ) 120-150mbytes/sec

a bare drive will handle several streams of HDV with breaking a sweat

a 2 drive array like this will handle 1 stream of uncompressed 1080/8bit at 24fps, 2-3 streams of uncompressed 720p24 8bit ( only 44mbytes/sec) and several streams compressed as ProRes (20ish mb/sec ) and many streams of HDV. the problem with HDV is the processor overhead will limit the number of streams before your storage.

only uncompressed requires big fast arrays. the compressed flavors will work off of single or 2 drive arrays quite nicely, right up until the last 10% or so of the drive. these modern drives are really very fast.