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Copy to hard drive from 2 dvds at one time

Last response: in Windows 7
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November 21, 2010 3:52:01 PM

Hello,I was wondering if there is any reason not to copy to a hard drive from two DVD drives at the same time. It seems to work ok but I have no idea if it will cause any data corruption.

I have windows 7 and two dvd drives that I am using to copy files
to a 2 tb hard drive.
a b $ Windows 7
November 21, 2010 5:21:22 PM

provided you have plenty RAM memory and processor space, no problem
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a b $ Windows 7
November 22, 2010 4:46:04 AM

There is no advantage in copying from 2 dvd's at the same time, it will not work twice as fast. Might be handy if you want to go and do something else during the process.
As long as the drives are both on seperate channels it also shouldn't be a problem.
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a b $ Windows 7
November 22, 2010 6:14:02 AM

Agree with above, can't think why it would cause a problem.
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a b $ Windows 7
November 22, 2010 6:37:39 AM

Jonmor68 said:
There is no advantage in copying from 2 dvd's at the same time, it will not work twice as fast.
Assuming he's copying two different DVD's to two different files . . . why wouldn't the two finish faster than if done one at a time?
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a b $ Windows 7
November 22, 2010 7:04:13 AM

The heads on the hard disk will be moving all over the place as it writes to both files at the same time. As head seeking is the slowest operation on a hard disk the copy speed will not be twice as fast - in fact it may well be slower than writing two single files sequentially.
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a c 353 $ Windows 7
November 22, 2010 1:00:26 PM

+1 ^

Best way to do this it to write a script that will copy from one drive, wait for process to end, and then copy from the second. That way you can kick off the script and walk away for 2 DVDs worth of data.
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a b $ Windows 7
November 22, 2010 3:18:51 PM

My assumption was that overlapping the relatively slow I/O speed of the DVDs and bufferring in memory and on the HD itself would cover the HD seek times. Especially since a user now has little control over what else the OS is doing that moves the HD heads somewhere else while copying one OR two DVDs lol.

And of course, if he were copying them to two different HDs the problem changes character completely. Copying two should be faster.

But you guys sound like you have done this before, so I'll trust your judgement . . . until next Wednesday lol. That's the first time I'll have the opportunity to be at my last remaining PC with multiple DVDs. I'm curious now, and will test and report back.
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a b $ Windows 7
November 22, 2010 7:13:01 PM

yes, separate channels.
maybe even two different software apps running will work also.
I hope you AT LEAST have a dual core unit and enough RAM, 4GB..
If not you'll be there forever..
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November 23, 2010 7:25:52 PM

Twoboxer said:
My assumption was that overlapping the relatively slow I/O speed of the DVDs and bufferring in memory and on the HD itself would cover the HD seek times. Especially since a user now has little control over what else the OS is doing that moves the HD heads somewhere else while copying one OR two DVDs lol.

And of course, if he were copying them to two different HDs the problem changes character completely. Copying two should be faster.

But you guys sound like you have done this before, so I'll trust your judgement . . . until next Wednesday lol. That's the first time I'll have the opportunity to be at my last remaining PC with multiple DVDs. I'm curious now, and will test and report back.



I have discussed this with a co-worker and he feels that since the DVD is so much slower than a hard drive it just might be twice as fast. I think I will test it myself for speed as the one time I did this I did not pay attention to how long it took but I think it did not take much longer than one disk. I have had the two drives copying to the same hard drive and it certainly looked like it did ok for data integrity. My main worry was data corruption if windows stumbled over it's own feet. It sounds like no one is worrying about windows corrupting the data and now the idea of how fast it will happen has come up.

I have a quad core intel pc at 3.0 ghz with 4GB of memory running windows 7 64 bit.
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a b $ Windows 7
November 23, 2010 9:51:55 PM

Don't worry about the data integrity reading 2 opticals in.

But being an old timer, I personally wouldn't count on burning 2 opticals at the same time. No reason, systems should be fast enough now, but just paranoid lol.
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November 23, 2010 10:14:34 PM

I sort of hesitate to report on the test I made but when I got home since everyone already has voiced their opinions. Anyway I set up the test for copying the dvds as follows.
First I made two new copies of a DVD. The total size of the files on each disk was 4.01 GB. Next I set up four folders on a new 2Tb WD green drive (the slower model). I could not put it all in the same folders as then I would have had duplicate files. See the setup below;
Test 1 A
Test 1 B
Test 2 A
Test 2 B

I opened a file manager window for each DVD and noted the time on my pocket pc.
Each DVD had three folders, forgetting to highlight (select) these folders ahead of time slowed me down on the two at once copy.

The first test I dragged the files of the first DVD to Test 1 A and then highlighted the three folders of the other DVD and dragged them to Test 1 B. I figure that I lost about 10 seconds with having to select the folders on the second drive.
The top drive finished about 15 seconds ahead of the second drive.

Total copy time was 5 minutes 31 seconds.

Next I dragged the files of the top DVD to Test 2 A. This copy took 5 minutes almost to the second.

Next I dragged the files of the lower DVD to Test 2 B. This copy took 5 minutes 25 seconds.

So I would believe from what I saw with my own two old eyes that I can copy two DVDs to one hard drive in the same time I could copy one.

Glad someone brought the question up as that was sort of interesting to do.
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a b $ Windows 7
November 23, 2010 10:19:59 PM

Thanks for doing the test!

I wonder how many DVD-to-HD tasks could be overlapped until overlapping took longer than sequential?

/looks around for someone with 8 optical disks installed ;) 
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November 23, 2010 10:31:52 PM

I forgot to mention that all of the drives involved are sata.
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