capture capability w/ UATA/66 drive

[BeTa]

I have a UATA/66 drive that I use for capture. However, when I use the AuxSetup benchmark to test the capture capability of my drive, I get a result of around 25000K/s for sustained write. Shouldn't I expect higher transfer rate?

Is there other tools for assessing ATA drives' transfer rate (I have EZ-SCSI for my SCSI drives)?

BeTa

[ktnwin]

25000KB/sec is typical for today's HDD. Some newer drives can score even higher (mid 50000KBS range).

UATA/66 (also called UDMA-66) gives a max transfer rate of 66MB/sec (66,xxxKB/S), but this does not mean the HDD itself can transfer that fast from the media to the PC. It's never meant to be.

For example, the most recent drives support UATA/100 but none of them score 100MB/sec.

Many may wonder why HDD manufacturers do this.
Here is the reason:

1) the media transfer rate get higher and higher with new models (mid 50MB/sec), if the host transfer rate (for example UDMA-33) of the drive is lower than the media transfer rate, the drive will have poorer performance. Non DMA transfer max out at 16MB/sec. This is why it is already recommend to set DMA mode for the HDD

2) the faster the host transfer rate (UDMA-33, 66 ot 100), the less time it takes data to transfer between disk and host

Hope this clarifies the HDD spec.

[BeTa]

If you look at the labDV web site about capture with Virtula Dub, (http://www.labdv.com/en/manuals/capture_virtualdub.htm),
it shows a benchmark result of 32,5xxK/s sustained write and 41,2xxK/s sustained read. I kind of expected the result with my UATA/66 drive to be similar...

BeTa

[ktnwin]

Hi Beta,

Is it the same drive model that was benchmarked ? If it is the same, then you have some setup issue. If it is not, then that could be normal.

Just to clear the matter a little more: let say you have a 40GB drive and it has 4 heads on it. Compare it with a 40GB drive with only 2 heads, the 2 head HDD will score higher thruput than the 4 head one.

Why: because to achieve the same capacity, the 2 head drive must pack a lot more data on a track than the 4 head one. This is called the BPI (bit per inch on the track).

How do you know the number of heads your drive has ? Tough luck, some manufacturer made it clear, some bundles that in the serial number of the drive. A sure way to tell is to look up for the model number in that manufacturer's Web site and look at the spec.

The higher is the BPI, the higher the transfer rate is. This is really what measured by thruput benchmark. The designation UDMA-33, 66 or 100 simply shows the maximum transfer rate (from the drive memory buffer).

[BeTa]

Thanks for the info, ktnwin.
I have all the specifications for all my drives. I will look into them... I made a habit out of collecting infomation re: my hardware.
BeTa