2Tb Hdds: 2¾" Or 3½"? Second Time, As Error In Question!!

[gl556tr]

* * * * * * REPEAT QUESTION * * * * * *
* * * * with incorrect word ("latter") replaced by "2¾"-HDDs" * * *
I am looking for a pair of HDDs with a capacity of ≥2TB, then pop them into an external enclosure with RAID 1. Then second similar enclosure for a secure backup.
With 2¾"-HDDs now offering such capacities, is there any advantage/DISadvantage is choosing this over 3½"?
Certainly, for the 2¾"-HDDs there would be less energy=heat-generation.
(Less important, but interesting: more and more have 3TB - so go for them if price & maker is good?)

[ChuckFickens]

Not sure where you'd find 2¾ inch drives! I assume you mean 2½ (please don't post another question correcting it!)

you've pretty much got it.... 2.5inch drives use less power and generate less heat. but they tend to be a bit slower than 3.5 inch drives and cost a little more for similar capacities.

The above is, however, a bit of a generalisation... a fast 2.5 inch drive will be faster than a slow 3.5 inch drive... but fast 2.5inch drives will bring the price increase into play even more.

Generally speaking, unless you are going for ultimate speed 2.5inch drives will do just fine and you must keep in mind what interface you will be using, for example, USB2 has a transfer rate of about 60MB/s and even fairly low end 2.5 drives can get upto about 80MB/s so in that case the slower drive wouldn't be the bottleneck anyhow (even for a single drive)... if you are going for network attached then a 1GB network connection has a theoretical top speed of about 125MB/s so the disk may become the bottleneck (especially in raid one read, not so much in write)

As for 3TB drives... they are not available in 2.5inch yet, and to be honest, the decision between 2TB and 3TB is one only you can make based on how much space you think you'll need.

Personally, I'd use 4 disks and RAID 5 though.