External FW 800 replacement HDD 7200 or 5200RPM

[mindquest]

I have an 2009 iMac (11,1) with a SSD (SATA 3) for the internal drive and use a firewire 800 external drive from OWC for my Time Machine back-ups exclusively.

I need to change out the external HDD (sadly the top limit is 2TB) and wanted to know if going to a 5200 RPM vs 7200 RPM would cause a bottleneck.

My choices for replacement HDD are:
$95 WD Red 2TB (5200 RPM) (WD20EFRX)

$132 WD Black 2TB (7200 RPM) (WD2003FZEX)

$149 WD RE 2TB (7200 RPM) (WD2000FYYZ)

If I don't need to pay for 7200 RPM why spend the extra bucks. But reliability and durability are my primary concerns. Any advice is appreciated!!

 

[Weaselboy]

If you are only using it for TM backups, speed is not going to be an issue. I would just get whichever is cheapest for you.

 

[mindquest]

So the bottleneck in the interface (SATA 3 => Firewire 800 => HDD RPM) is not the HDD but one of the other two (firewire or SATA 3)?

 

[Weaselboy]

So the bottleneck in the interface (SATA 3 => Firewire 800 => HDD RPM) is not the HDD but one of the other two (firewire or SATA 3)?

No... the hard drive is the bottleneck. But for a Time Machine backup drive whether say the 7200 is maybe ten percent or so faster than a 5200 is not going to matter. If you were using the external for work and moving large files back and forth all the time, I could see fretting over speeds and paying more money for faster speeds. But just for a backup drive with Time Machine, who cares if it can complete a backup in ten minutes vs. twelve.

 

[mindquest]

No... the hard drive is the bottleneck. But for a Time Machine backup drive whether say the 7200 is maybe ten percent or so faster than a 5200 is not going to matter. If you were using the external for work and moving large files back and forth all the time, I could see fretting over speeds and paying more money for faster speeds. But just for a backup drive with Time Machine, who cares if it can complete a backup in ten minutes vs. twelve.

Thanks for the reply!!