Why are my DVD drives slow?

[Guest]

I have a Dell computer with an Intel E8200 cpu, 2 GB of RAM, running
Vista Home Premium. It has a Philips/Benq DH-16W1S 16X DVD writer,
and a ASUS E616A3T 16X DVD-ROM drive. They are both SATA and plugged
directly into the motherboard, each one into its own SATA channel.

I just took a DVD+R disc with 3.84 GB of data on it, and put it into
the ASUS drive, and then copied all the files onto the hard drive. It
took 450 seconds, which is a transfer rate of 8.5 MB/s. So that means
the read speed of the ASUS drive is a little over 6X, even though it's
supposed to be a 16X drive.

Then I burned the 3.84 GB of data from the hard drive onto a 16X
Verbatim DVD-R disc. It took 315 seconds, which is a transfer rate of
12.2 MB/s. That means the write speed of the Philips/Benq drive is a
little over 8X, even though it's supposed to be a 16X drive.

Any idea why both of the drives seem slow?

 

[Paul]

I have a Dell computer with an Intel E8200 cpu, 2 GB of RAM, running
Vista Home Premium. It has a Philips/Benq DH-16W1S 16X DVD writer,
and a ASUS E616A3T 16X DVD-ROM drive. They are both SATA and plugged
directly into the motherboard, each one into its own SATA channel.

I just took a DVD+R disc with 3.84 GB of data on it, and put it into
the ASUS drive, and then copied all the files onto the hard drive. It
took 450 seconds, which is a transfer rate of 8.5 MB/s. So that means
the read speed of the ASUS drive is a little over 6X, even though it's
supposed to be a 16X drive.

Then I burned the 3.84 GB of data from the hard drive onto a 16X
Verbatim DVD-R disc. It took 315 seconds, which is a transfer rate of
12.2 MB/s. That means the write speed of the Philips/Benq drive is a
little over 8X, even though it's supposed to be a 16X drive.

Any idea why both of the drives seem slow?

Optical recording actually has a number of different rotational speed
strategies. A couple are shown here.

http://en.wikipedia.org/wiki/Constant_Angular_Velocity
http://en.wikipedia.org/wiki/Constant_Linear_Velocity

Sites like CDFreaks or cdrinfo, show the results of speed testing
tools, and they demonstrate whether CAV, CLV, or some variant of
those, is being used. A number of speed curve examples are shown
on this page.

http://www.cdrinfo.com/Sections/Reviews/Print.aspx?ArticleId=12802

If your burning software, has a tool to verify read speed, it will
show a curve. The maximum transfer rate in the curve, might be the
quoted speed for the drive. So a 16X drive might only be 16X at
the end of the disc. You do a read speed test, on a disc that is
burned and full of data.

Something like that.

Also, random file access (copy files from optical disc to hard drive),
involves a lot of seeking. The optical drive might have a full stroke
seek time of 110 milliseconds or more. That is a large period of time,
during which no files will be copied.

Burning, on the other hand, is sequential, and the controller in the
optical drive plus its little microcontroller, precisely control the
rotational speed profile as data is written.

The speed test tools, do linear reads of contiguous sectors. That
means you don't have a lot of random seeks to degrade performance.

Paul

 

[GT]

I have a Dell computer with an Intel E8200 cpu, 2 GB of RAM, running
Vista Home Premium. It has a Philips/Benq DH-16W1S 16X DVD writer,
and a ASUS E616A3T 16X DVD-ROM drive. They are both SATA and plugged
directly into the motherboard, each one into its own SATA channel.

I just took a DVD+R disc with 3.84 GB of data on it, and put it into
the ASUS drive, and then copied all the files onto the hard drive. It
took 450 seconds, which is a transfer rate of 8.5 MB/s. So that means
the read speed of the ASUS drive is a little over 6X, even though it's
supposed to be a 16X drive.

Then I burned the 3.84 GB of data from the hard drive onto a 16X
Verbatim DVD-R disc. It took 315 seconds, which is a transfer rate of
12.2 MB/s. That means the write speed of the Philips/Benq drive is a
little over 8X, even though it's supposed to be a 16X drive.

Any idea why both of the drives seem slow?

I suspect that you have been sucked in by marketting - the 16x is probably
read speed at the fastest part of the drive and the write speed is probably
significantly lower.

Normally drives are quoted with a read speed and a write speed, but
obviously for sales, they only quote the fastest number in the name.