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5400 vs 7200 External HD Performance?

R

rossip

macrumors regular
Original poster
Feb 13, 2011
183
0
I'm interested in getting an external Hard drive for my iMac 7,1. Specifically I'm looking at the OWC Mercury On-The-Go Pro (http://eshop.macsales.com/shop/firewire/on-the-go). I'm planning on using it with Firewire 800, and my question is whether or not The 7200 RPM model would provide any significant performance advantage over the 5400 RPM. Based on the benchmarks on OWC's website, it looks like the Firewire 800 port might be a bottleneck to both drives achieving there maximum Read and Write speeds, as there performance is both approximately identical.

http://eshop.macsales.com/item/Other World Computing/MS8U5500GB8/

http://eshop.macsales.com/item/Other World Computing/MS8U7500GB16/

(See the benchmark tab)

Thanks for any advice you can give me!
 
I'm also interested in Daisy Chaining two HD, one for time machine and the other for iMovie. Does anyone have any suggestion regarding this and performance?
 
The media transfer rate on the Hitachi is 1004Mb/s. This is already higher than the speed the firewire connection is capable of providing.

Used externally, you would see no speed difference between these two drives.
 
DannySmurf said:
The media transfer rate on the Hitachi is 1004Mb/s. This is already higher than the speed the firewire connection is capable of providing.

Used externally, you would see no speed difference between these two drives.
Click to expand...

OK, this is what I thought. It surprises me that they would sell 7200 RPM external drives with connections slower than its max speed, with no real advantage over 5400.
 
rossip said:
OK, this is what I thought. It surprises me that they would sell 7200 RPM external drives with connections slower than its max speed, with no real advantage over 5400.
Click to expand...

Why wouldn't they? Some people will just look at the specs, assume 7200 will always be faster, and spend the extra money.
 
DannySmurf said:
The media transfer rate on the Hitachi is 1004Mb/s. This is already higher than the speed the firewire connection is capable of providing.

Used externally, you would see no speed difference between these two drives.
Click to expand...
That's not true! The seek time will be lower with a 7200 RPM drive. Also, the transfer rate of a rotational medium is not consistent across the disk, since the linear velocity of the disk increases as the head moves towards the outer edge (the angular velocity is constant). Depending on the amount of data stored on the drive, how the data is physically arranged, how the drive is partitioned, etc. the drive can be a bottleneck even with limited transfer speeds at the interface. There are occasions where a 7200 RPM drive will thus be faster for sustained transfers, too.
 
Bill Gates said:
That's not true! The seek time will be lower with a 7200 RPM drive. Also, the transfer rate of a rotational medium is not consistent across the disk, since the linear velocity of the disk increases as the head moves towards the outer edge (the angular velocity is constant). Depending on the amount of data stored on the drive, how the data is physically arranged, how the drive is partitioned, etc. the drive can be a bottleneck even with limited transfer speeds at the interface. There are occasions where a 7200 RPM drive will thus be faster for sustained transfers, too.
Click to expand...

Honestly, I was wondering if this would be a factor. So would it be accurate to say that the 7200 RPM would hit 80 MB/s more constantly when reading and/or writing? Regardless, would you say the difference is marginal compared to 5400 RPM, or can this manifest itself in a noticeable and significant way?
 
rossip said:
Honestly, I was wondering if this would be a factor. So would it be accurate to say that the 7200 RPM would hit 80 MB/s more constantly when reading and/or writing? Regardless, would you say the difference is marginal compared to 5400 RPM, or can this manifest itself in a noticeable and significant way?
Click to expand...
I would say it depends on the intended use of the disk, the individual disks themselves (as performance can vary across brands and models), and how full the disk will be. For sustained writes, if you plan on having only one partition and never come close to filling the disk, the difference may be nonexistent. If you work with many small files, the difference in seek times may make the 7200 RPM disk feel more responsive.

I usually say to go with the best you can afford. In this case, however, it may not be worth going for the 7200 RPM drive if you're usage patterns don't justify the expense. The other day I saw a 500GB 7200 RPM drive on sale for $60 (the deal has since expired), so it may also be worth finding a similar deal and going for the 0GB kit, which may even end up being the best deal of all. HTH.
 
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