Better aerial density...

[opentoe]

The Hitachi 7K3000 2TB drive uses 411 aerial density. The WD Black 2TB drive uses 500 aerial density. Would it be safe to assume given that both drives have 64MB cache the WD will perform a little better?

 

 

[BRiT]

This depends largely on the firmware each drive is running and what they're tuned for. There have been drives in the past with twice the cache as other drives yet they performed slower despite all other items being equal. There have even been firmware updates which have increased performance in a benchmark or two while ending up slower in real life usage patterns. It's easier to tune firmware to win certain benchmarks than to adjust to a wide variety of actual usage.

 

However, based on those numbers and the 5940rpm vs 7200rpm, I would be inclined to think the WD 2TB Black drive would be the better performer.

[S80_UK]

Thought we were having an RF discussion for a moment...    For what it's worth, it's areal, nor aerial.  The latter is for radio / tv reception

[abq-pete]

I think those are both 7200rpm drives.  Hitachi has the 7K3000 and the 5K3000 (the 5940rpm) series.

 

Regards,  Peter

[KYThrill]

The Hitachi 7K3000 2TB drive uses 411 aerial density. The WD Black 2TB drive uses 500 aerial density. Would it be safe to assume given that both drives have 64MB cache the WD will perform a little better?

 

 

 

The WD Black is a little faster on single-thread operations.  But the Hitachi is faster when multi-threading.  The test results I've seen showed the WD Black's I/O slowing down significantly with more than one thread.  One thread the WD Black was a little faster.  Two threads the Hitachi was a little faster.  Three threads the Hitachi was significantly faster (four threads on a Hitachi had basically the same I/O as two on a WD Black).  In comparison, enterprise drives like the WD RE4 ran circles around both drives when multithreading.

 

Generally, the more expensive enterprise level drives can handle more simultaneous file I/O requests in a more efficient manner.  You get some of this improvement in the Hitachi drives (but still not to enterprise levels).

 

I don't know exactly to what amount that will help you in unRAID.  It may help a little if you are reading and writing to the drive at the same time on data drives (watching a movie and copying to the drive).  I think the primary benefit would be in the parity drive.  Write to five HDD's at once and the parity drive will be getting hit with multiple I/O requests to update parity.

 

I typically recommend a Hitachi 7200 rpm drive for parity and then green drives for all the rest of the data drives.  I think that is the sweet spot on the price/performance/heat curve in most typical applications.

 

EDIT:  I just noticed that you stated the 7k3000.  All my experience is with the 7K2000, five platter design.  I have seen no performance reports on the 7k3000.

[opentoe]

WD RE4 sounds good for a parity drive.