[gentoo-user] Re: Hard drive RPMs and data speed.

[Nikos Chantziaras <realnc@arcor.de>]

On 10/27/2011 11:15 AM, Dale wrote:
> Howdy,
>
> I'm wanting to get a hard drive that is pretty good size. I'm looking
> for about 1 to 2TBs or so. Thing is, a lot of them seem to be 5900 or
> even 5400 rpm drives. I realize that the data on there is packed pretty
> tight so I want to ask a few people that may have one or more of these
> things a few questions. Are they as fast as a slower RPM drive?

I assume you meant to say "as fast as a faster RPM drive".  No, of 
course not.  If we're speaking about the same capacity and amount of 
platters, of course.  If we're not, then yes, they can be as fast 
because of the higher data density.


> Would
> they be fast enough to play HD videos and such? I have quite a few 1080
> HD videos. I don't want the drive to cause issues.

The transfer speed required for playing HD videos is virtually zero. 
1080p video compressed using an 8mbps rate require 2MB/s.  This can be 
done even with the slowest drive from 10 years ago.  Today's slowest 
drive are able to play about 40 or 50 of those HD video simultaneously. 
  So the answer is yes.  They can play HD video :-)

Most of those 5900/5400 disks are meant for pure data storage.  The 
lower RPM is used to market them as "green and silent", meaning they 
don't consume much power and aren't noisy.  Installing your OS on them 
though isn't going to give you good speed.  They have good transfer 
rates, but their access times usually suck.


> Can someone that has one or more of these post their hdparm -Tt results?
> Different speeds would be great too. I'd like to compare what a 5400rpm
> drive would do compared to a 7200rpm drive.

Simply Google around for benchmarks of the drivers you're interested in. 
  Note that is in area where it doesn't make any real difference that 
the benches or reviews you find are performed under MS Windows.  The 
results are applicable to every OS.

As a rule of thumb when buying drives: if you want to install software 
on it, buy an 7200RPM drive with good access times.  Of course they're 
more expensive  If you just want to store all your downloaded HD porn 
and music collection on it, a silent 5400RPM drive is a good choice.

Oh, and one other thing; hdparm is only meant to get you the continuous 
I/O transfer rate.  It's an awful benchmark for anything else, like what 
happens if a file is fragmented or how fast it can copy/write data 
spread around the disk, how good it is at combined random I/O operation, 
etc.