2.5 inch drives versus 3.5 inch drives

I am looking for some publicly available comparisons between 2.5 inch drives and 3.5 inch drives. What I had assumed is that a 2.5 inch 15k drive and a 3.5 inch 15k drive would have identical performance, however I was shown some benchmarks recently claiming that 2.5 inch 15k is considerably faster, and 10k 2.5 inch is about the same speed as 15k 3.5 inch. The problem is that these benchmarks can't be reproduced by most people because of the platform they were done on, and more to the point, it's the underlying disk that I was hoping to compare.

Basically, will a mainframe using some number of 3.5 inch 15k drives right now perform about the same as a mainframe using an identical setup of 10k 2.5 inch drives?

Solution 1:

Here are some benchmarks for 2.5" drives:

http://www.tomshardware.com/charts/2009-2.5-mobile-hard-drive-charts/IOMeter-2006.07.27,1130.html

Here are some benchmarks for 3.5" drives:

http://www.tomshardware.com/charts/2009-3.5-desktop-hard-drive-charts/IOMeter-2006.07.27,1034.html

Taking a look at the top 500GB drive in each section shows us that there is a difference of 36IOPS between the 104 IOPS scored by Seagate Barracuda 7200.12 and the 140 IOPS scored by the Western Digital WD Scorpio Black. The first is a 3.5" drive and the second is a 2.5" drive and they both have a 16MB cache.

Because the size of the platter is smaller, one would argue that the seek speed will be faster on a 2.5" drive, as opposed to a 3.5" drive.

It's difficult to say whether having, for example, 12 x 2.5" 10K RPM drives or 12 x 3.5" 15K RPM drives will yield the same or different performance without testing them in your environment, simulating the sort of work that will be done using these drives. Depending on the RAID configuration and RAID card used, performance could also vary wildly.