Drives: RPM v. Seek Time

[bongolation]

Man, I am so confused!

I'm _trying_ to build a computer for a DAW, but am continually finding myself stymied by hardware selection questions.

OK, I am going to run two HDs RAID, and I know that I want fast seek times. I also see that people recommend 7200RPM drives.

What I don't understand is this: What is the significance of high RPM drives? There does not appear to be any direct correlation between RPM and seek times, as I see slower RPM drives with faster seeks times than another drive with a higher RPM. I also see drives of the same make and capacity with identical seek times, but have different RPMs.

One tech I consulted about this said that the bottom line was seek time and to get the fastest seek times I could and not to worry about RPMs, and that for a DAW the higher-speed drives produced somewhat higher acoustic noise in the box anyway.

Someone explain this mystery to me, please!

 

[Lambo]

A 7200 RPM /ata100 hard drive is the ticket. You definitely want the quicker spin you get with the 7200 RPM but you also need the faster transfer rate in (100megs per sec). Some motherboards such as the DFI that I have only support 66meg transfer rates and therefore require an ata 100 PCI card in order to achieve the 100meg transfer rate. The difference is staggering.

 

[vox]

Hard Drives record data as concentric rings on the drives platter, the data is read by a 'head' which is mounted on an arm, sort of like a record player. The seek time basically refers to how fast the arm can switch from one ring of data to another, the RPM of the drive will basically tell you how fast data can be streamed once the read arm has settled in place since a 7200 rpm drive will complete one revolution of the platter faster that a 5400 rpm drive. There are other factors as well, how long the arm takes to 'settle' after it moves etc.

So a 7200 rpm drive could *theoretically* be slower to access data than a 5400 if it has a bad seek time and the data is fragmented.

Snoop around on sites like this one:

http://www.storagereview.com/

You should find helpful info.

Good Luck

 

[MrBoogie]

Another important thing. I'm pretty sure the terms ATA/100 and ATA/66 and so on refer only to the maximum BURST transfer rate. NOT the sustained transfer rate.

Therefore, an ATA/100 drive is not necessarily faster than an ATA/66 drive. ie, I have a 5400 ATA/100 that is definitely slower than my 7200 ATA/66 Diamond Max.

I would think the sustained transfer rate is the most important spec of a hard drive.

Romeo

 

[Emeric]

You sure you want to do raid? Do you really think it's necessary?

IMO just use 7200RPM drives, buy a few removable brackets for swapping drives around, optimize your system etc.. and call it a day. Try it and see. Transfer rate is the least of the problems. You will never see 100MB/s in IDE. Not at the moment. SCSI, yeah if you got the $$ to burn, do it. But, is it necessary?