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Video RAID vs 7200 RPM EIDE?

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rd4
Video RAID vs 7200 RPM EIDE?
by
on Feb 19, 2003 at 2:25:11 am

I bought my Medea 50/2 Video Raid and DV500 card from videoguys a couple years ago and I'm now finally getting serious about video editing....I've just upgraded from a Dell 450 to a Dell Precision 530 with dual Xeon 1.8ghz processors, 1 GIG RAM, and internal SCSI HD and I'm running Windows XP professional. But now here's my dilema - - I'm getting dropped frames because my Medea is moving so slowly. Here are the details:
The 530s come with an Adaptec SCSI controller built into the mother board (AIC-7892 Ultra 160 PCI) and it came with a 36GIG SCSI 10,000 RPM internal drive. I have connected my external 50 GIG Medea Video RAID HD by using one of the internal ribbon connectors attached to a PCI opening external 68 pin SCSI connector. The drive works but after using a speed test utility it shows the transfer rate at about 2.5 MB/sec!!!(very slow) My internal EIDE 120 GIG HD 7200 RPM measures out to 48 MB/sec. and my 10,000 RPM SCSI intneral HD runs at about 30 MB/sec. I understand you need at least 20 MB/sec HD transfer rate for high quality video editing?
So, I have the choice of spending a couple hundred bucks for a good SCSI controller card so that I can use my Medea 50 gig SCSI Video RAID external hard drive (original cost three years ago from was $799) or now that EIDE drives are so fast and cheap (I bought my 120 gig EIDE drive for $200) shouldn't I just go for another one of these and sell the video RAID? I'd spend about the same amount of money but would wind up with more than twice the HD space and a little more desk top space as well? Is there something I'm missing here? Does this sound like the right approach? Or does the Video RAID give me something the EIDE drive cannot?
thanks for any input,
Ron DeFore


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ciabt
Re: Video RAID vs 7200 RPM EIDE?
on Feb 20, 2003 at 10:26:08 pm

Hi there
I'm by far no export on Raids but I'm pretty sure it should have a much higher sustainable transfer rate than 2.5 MB/sec. Perhaps someone on here can give you tips on how to speed it up. I've never had a raid so the only tips I can give apply to normal hard drives, but might help speed up your raid. My first tip is to make sure that there is at least 15% free space on your raid as hard drives have to work so much harder and get so much hotter when there is less than 15% free space. My second tip is to make sure that its nice and clean and no dust (causes alot of heat) and that your raid is properly cooled (hard drives will run alot slower and not work properly if they are overheated). My third tip (I'm not even sure if you can do this with a raid) is to defrag the hard drives. These are about my best suggestions that I can think of to improve your performance. Perhaps someone can read through these and let you know if they can be applied to a Raid. As for your question about regular EIDE drives, it depends upon what kind of camera's/quality you want. A regular 7,200 rpm hard drive can give you enough sustainable transfer rate to capture full quality uncompressed DV (approx 4MB sustainable). If you have DVCAM or Beta or somthing requiring broadcast quality , you will need a video raid, as fully uncompressed video needs somewhere around 30MB per second sustainable transfer rate.And the hard drive will eat up about 1 gig every 30 seconds. So it really depends upon what kind of camera's and what you are creating your video's for. I just use a 120gig 7,200 RPM Western Digital Hard drive for my video files and it runs very well and has never dropped a fram (knock on wood). If you are just using DV I would suggest selling your raid and buying 1 or 2 hard drives and it will save you a ton of money and probably give you a few hundres Gigs more of space. Good luck with your decision, if you have any more questions, please feel free to ask!
Later
Brent


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Ron Evans
Re: Video RAID vs 7200 RPM EIDE?
on Feb 21, 2003 at 12:20:46 am

All the DV25 formats have about the same data rates since they use the same compression. DVCam tape runs at 50% faster than DV and as such uses more tape to record the same data content thus less likely to suffer from drop outs, or more to the point lets the error masking have an easier job of fixing any problems. DVCPro runs slighlty faster than DVCam for the same reasons and has an extra cue track and linear control track which ups the data rate just a little more but all these are less than 4MBs since they are nominally all 25Mbs encoding. DVCam and DVCPro were intended to allow linear editing in legacy edit suites which is why they have locked audio etc. Once every one went to NLE the advantages over the consumer DV standard are slim the difference in camcorders and decks is however significant. JVC and Panasonic now have Pro gear running at the consumer DV speed but with locked audio for greater editing accuracy.
As far as hard drives are concerned most 7200 rpm eide drives are more than adequate for even multi track video editing. The complement should be a small boot drive and a number of a/v storage drives.
I agree that for DV ( any format ) sell the RAID and get some modern 7200 rpm drives.

Ron Evans


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