Hard Drive speed question

[Khalil]

I know that with IDE if you have 2 hard drives running at 2 different speeds, as in one at 7200 RPM and other at 5400 RPM they both end up running at 5400 RPM

With SATA is that the case as well?
If you have a raptor 10k RPM and regular SATA 3.0 7200 RPM in the same machine hooked up to 2 different SATA channels on the mobo do they both end up running at 7200 RPM?

[Alaron]

That is not true. Hard drives spin at their rated speed, no matter which drives they are paired with in a system.

[Khalil]

That is not true. Hard drives spin at their rated speed, no matter which drives they are paired with in a system.

What about the seek and write times are they effected?

[Panama Red]

Alaron is correct. I was fed that same misinformation about hard drive speeds some years ago and had to do some research to clear it up. Combining memory of two different speeds will cause the faster one to run at the speed of the slower but not hard drives. Hard drive speed is rotational/physical movement while memory speed is electrical/data movement rated.

edit: Nope, seek and write times are independent also.

[Khalil]

Ok great thanks guys, now I have another question.
Can I raid 2 hard drives that are different size and different speeds as in 1 Raptor and regular Sata?

[Stuey]

Ok great thanks guys, now I have another question.
Can I raid 2 hard drives that are different size and different speeds as in 1 Raptor and regular Sata?
As far as I know, no, you cannot. You need two identical drives. The same *might* not be true for larger arrays of different RAID types, but it holds for RAID 0 or 1.

[Cricket]

I know that with IDE if you have 2 hard drives running at 2 different speeds, as in one at 7200 RPM and other at 5400 RPM they both end up running at 5400 RPMYou're confusing the HDD RPM with the data transfer rate. It was the older IDE/ATA controllers (that used the 40 wire cables) that the burst data transfer rate would run at the the slower of 2 HDDs on the same controller (if there were a ATA33 and a ATA66 HDD on the same controller, both HDDs would transfer data at ATA33 speeds). But with the newer EIDE/ATA controllers (that use the 80 wire IDE cables) that the hard drives would transfer data at their given data transfer speeds. But this is all moot now that SATA HDDs are the norm.

:) Cricket

[glc]

Why do you want to RAID in the first place? The only RAID I trust is in servers using an advanced RAID such as RAID 5. RAID 0 is a marketing gimmick and removable media is a better way to keep backups than RAID 1.