Similar hard drives - why the massive difference in write speed ?

[Grant]

i was checking some ext drives at my place.

These 2, are both are WD 500GB sata drives connected by usb.
however, one is a 2.5", the other a 3.5" (if that makes a difference)

the read speeds are very similar, however, the write speeds are massively apart.

why would that be ?

 

[DA-LION-619]

3.5" is bigger, spins faster etc.

 

[gregmcc]

Yip - higher spindle speeds. You will probably find there is also more cache on the 3.5 inch drive.

 

[Grant]

3.5" is bigger, spins faster etc.

spins faster ?
drives, be they 2.5" or 3.5" spin at 5400rpm / 7200 etc
these are both "vanilla" 5400rpm drives

 

[HavocXphere]

spins faster ?
drives, be they 2.5" or 3.5" spin at 5400rpm / 7200 etc
these are both "vanilla" 5400rpm drives

eh...no.

Imagine a carousel...the further you are from the centre the faster you go at any given rpm.

 

[CataclysmZA]

There will also be differences in drive controllers, cache sizes, platter densities and how they organise information and where the data is on the disk itself. Write speeds of laptop drives are lower typically because it has to make do with a single platter for information storage, usually. Desktop drives can cram in two or three platters into a much larger and taller shell, increasing write speeds.

The read speeds are similar because you're pegging the USB 2.0 specification's top speed. I'd wager that the USB controller you're hooking these drives to isn't great either, since 8MB/s write speeds is dreadfully poor even for a laptop drive. Plug those puppies into a SATA port and watch the speeds climb to close to their proper ratings.

Rather use Crystakdisk Mark for a better test of your drive speeds.

 

[ponder]

however, one is a 2.5", the other a 3.5" (if that makes a difference)

In that case they are not really similar for reasons mentioned above. You are not going to get the same performance from a 2.5" drive as you would from a 3.5" one.