Does this speed sound right?

[wh427]

Hey everyone. I just did a little work on my PC and am looking for a sanity check. I built my PC a few months ago and was running with just a SATA drive. Today I installed a WD 120GB EIDE drive for backups & MP3's as a master on the Primary IDE channel. When I went to copy my MP3 files (~50 GB) from the SATA drive to the EIDE drive, it said that it was going to take about 50 minutes. Does that sound right? If not, what should I check to speed things up? Thanks!

[flanzig1]

50 gigs in 50 minutes does sound right. And remember that is an estimate, so figure a 10 to 20% either side of 50 minutes.

[wh427]

Ok... but then, this doesn't make sense to me. If the drive is ATA/100 that means it can transfer 100MB/s, right? If I want to move 50 GB, that's 50000MB. So (going back to my college days here :) ) (50000MB)*(1s/100MB)=500s or just over 8 minutes. I realize that the HDD won't perform at peak rates all of the time but, having it take 50 min, that's a pretty large difference. Am I missing something in the math?

[Mesaeus]

An ATA 100 drive does not usually get 100Mb/s. Think more along the lines of 40-50 Mb/s, and that's the burst speed, which you almost never get in every day use. ATA 100 just means that the drive can theoretically get that maximum data transfer, but most hard drives barely get above ATA 66. No the 50 Gig/50 minutes seems about right.

Edit : further more, writing speed of hard drives is always a lot slower than reading speed, and in this case the writing speed is the limiting factor. Plus, everytime the hard drive has to move a head, it loses a relatively big amount of time. Like I said, theoretical burst speeds are never reached in practice.

[RJ]

Well, it takes longer to copy a large amount of small files than one big file. If you had a 50 GB AVI file, you could copy it in about 20 minutes. But because you have many small ones, it takes longer.

RJ

[glc]

This is why I pay no attention to max theoretical burst speeds. I'm still running at only ATA33 here even though I have a couple ATA66 capable drives. Just the fact that they are 7200 rpm drives instead of 5400 rpm has more to do with speed than the ATA rating.

[wh427]

Actually, last night I got to messing around with my BIOS and noticed that I had disabled UDMA on the primary IDE channel. I re-enabled it and tried to copy the files again. The time dropped to just over 20 minutes... :D