[jcroberts]

  >In terms of online gigabytes per watt, SSDs will 
  >lose out badly to traditional hard drives.

Incorrect. You forgot time. Think about it this way (with very rough numbers); The traditional Raptor drive will move data at 70 MiByte/s. These new SSD's move data 700 MiByte/s. Assuming that they both consume equivalent power, this new SSD will have a gigabyte-per-watt rating TEN TIMES BETTER than traditional drives.

[atonse]

I think the parent poster is talking about the amount of storage, not the rate of transfer. And in that metric, seeing how you can get 1TB hard drives for $70, I don't see that changing anytime soon.

Of course, it seems wasteful to need insanely fast access to things like movies or media/archival data in your home library.

[jcroberts]

If even if reitzensteinm was talking about capacity-per-watt, he's still wrong. The specific drive he mentioned was the "Raptor" model but that's an old, slow, small (150G) and power hungry (9.5W) disk. The newer WD "VelociRaptor" 10K RPM disk is more likely what he meant, and is a more fair comparison. The new Velociraptor only has a 600 GB capacity. The highest capacity OCD IBIS drive is 960 GB.

http://www.wdc.com/en/products/Products.asp?DriveID=821 http://www.ocztechnology.com/products/solid-state-drives/hsd...

OCD IBIS Power: 6.6 Watts Idle 9.5 Watts Active

WD VelociRaptor Power: 4.30 Watts Idle 6.20 Watts Active

Now we do the math. A total of 9600 GB would be 10 OCD disk or 16 VelociRaptor disk.

16 x 6.20 = 99.2 --WD VelociRaptor

10 x 9.5 = 95 --OCD IBIS

Similar is true for idle.

If we were not limited to VelociRaptor, when you get into some of the very slow but very huge disks (1-2 TB), sure, you could beat the rather specific OCD IBIS models on Capacity-Per-Watt. But it is very unfair to open only one side of the rotating vs. ssd comparison to every disk made, and there are higher capacity SSD's with even better power consumption numbers than the OCD IBIS.

As you noted, the metric of Cost-Per-Capacity is often 10 or more times more favorable for rotating disks. If you don't have a valid _need_ for the speed offered by SSDs, they are certainly not worth the added costs.

[reitzensteinm]

I honestly don't think we'd disagree on much if we sat down over a beer and discusse the issue. I'm as excited about SSDs as you are, and it seems that, from your above post at least, you agree that speed is the primary driver in SSD adoption right now.

It was not my intent to be argumentative - I just read your post and thought, power consumption as a benefit, are you sure you've done the math on this?

By the way, I couldn't find any 2 TB drives that were not PCI-X, so I do stand by my original analysis. With 1 TB SSDs, you'll still need 2x the servers. If you can piece together an SSD solution, ignoring cost, and including server wattage that can beat out an array of 2 TB drives on wattage, I will retract my original statement. You can use the idle power as the active power for the drives.