2.5" vs 3.5" externals

After several hours of browsing reviews about external harddrives I still havent found the answers to some of my questions.

I plan on getting an external harddrive for my laptop which I will be storing and frequently playing video files from (anywhere from 20 to several hours of playback). I'm having some confusion, however, between what would be best for me.

Can anyone answer what the major differences between a 2.5" and a 3.5" external harddrive would be (aside from the size)? Specifically, heat output, external power vs power through USB, reliability and 7200 vs 5400 rpm all in the context of a primary video playback drive.

Just in case, I have a Dell Inspiron 1501 and will be connecting the HD through USB.

 

Probably your biggest concern will be that, with the 2.5 drive, you will be running it off your laptop battery, which will run down faster. Whereas with the 3.5 drive it has it's own power. Another consideration is that the 3.5 will be much cheaper than the 2.5 for the same capacity. So if you don't mind carrying around the physically bigger 3.5, that would be the way to go.

 

The main differences are capacity and power. You can get a 3.5 external up to a TB(or more if they raid them), however, for the time being, you are limited to 500gb(which is still a LOT) on 2.5" drives. Also the 3.5" externals have to be plugged in to the wall, where the 2.5" drives can run off 5v USB power.

 

Thanks for the quick replies. That about answers my questions I think, and reminded me of a few things I left out.

I'm getting the external to transfer my storage drive from my desktop to while I'm over seas. That said, I only need 300-500GB. Also, while I dont mind having to plug it in, the added mobility as well as running off the laptop battery if i'm out of the house are appealing to me--though most of the time I will be at home while playing videos, so it's not a huge issue.

That said, from what you replied it seems that performance-wise there isnt much of a different between the two? Assuming 300 GB was fine for me, and having to plug one in as a side issue, would there be any major performance issues between say a WD mybook and WD passport?

 

The mybook is going to run at 7200RPM, where the Passport, as far as I know, are still only using 5400RPM drives. This is a bit of a moot point tho, as you aren't likely to notice the difference over the slow USB 2.0 bus.

 

Personally I don't like the MyBook enclosures (I have one). It is larger than a regular 3.5 enclosure (I have two of these). I also have a WD Passport and if the 7200 rpm speed is not needed, I would go with the Passport.

 

For transferring large files USB will be the bottleneck. For random access 3.5 will win even thru USB. And performance might be better real world as everything to do with HDD is not maximum bandwidth note 3.5's at the same RPM speed are faster in all ways.

 

I respectfully disagree. If both drives were the same capacity (ie.320gb) and the same RPM (ie 7200rpm), theoretically the 2.5" would have a better transfer rate due to higher platter density. This is one of the reasons WD chose a 2.5" drive for the new VelociRaptors.

 

I will respectfully say you have a point in theory. I will now bring up a point you must consider. Let us because just fun and theory talk about the outer most edge of the two disks? well 3.5X3.14= 10.99 inches? 2.5X3.14=7.85 inches. So in one revolution the 3.5 travels 40% more distance than the 2.5 in relation to the outer edge? So for almost 1/3 the outer edge of the larger disk will effectively have a speed advantage over the smaller, of 40% assuming they both moved in equally. So consider that? And to be honest I was generalizing. Of course you can find older desktop HDD that are slower than newer notebook.

I looked up your WD VelociRaptor™ and well they still make 3.5 also. Seems like they made 2.5 mostly for blade servers? Why they stop at 300GB's on a 3.5 is their own business. Your correct but if they made it 500GB's it likely would out perform 2.5. As it stands they have the same stats and that does have to be because of areal density. So yea you got me.

But in theory a 3.5 could be made kick a 2.5 up and down the street because of what I mentioned. So 3.5 at the same RPM will always be faster all else being equal so to speak/ not same size.

 

Hmm. You do make an interesting point and I will concede that towards the outer edge, there very well could be a performance improvement. Good call.

However, as far as the VelociRaptor is concerned, they truly only make then in a 2.5" form factor. The 3.5" model is nothing more than a 2.5" wrapped in a huge heatsink.

 

Just for reference, see here for the effect of the USB interface on the data transfer rate compared to eSATA (which is the potential performance).

I recall the OP is planning to take the HDD overseas. In this case I would recommend 2.5" (more than one if necessary) since they can be easily carried in the hand baggage. A 3.5" HDD in enclosure plus PSU could be put in hand baggage but it is somewhat heavier. Also, the 2.5" HDDs are designed for mobility and have much better shock ratings.

John

 

Having carried around both 3.5" and 2.5" externals, I must say that the 2.5" is much much easier to bring with me, whether it's to school, around town or a long term trip. It fits in my laptop case without issue, whereas my 3.5" doesn't really fit comfortably. In addition, the 3.5" has power cables and a stand which just take up extra space I don't have.

Regarding power, I prefer the 2.5" which sucks power from the laptop. This is because if you are near a power outlet, you'll be on AC power for the laptop, and if you aren't, the 3.5" won't run anyway. So moot point IMO

I can't say I know much about 2.5" vs 3.5" speed comparisons, but my 2.5" is definitely slower than my 3.5"--I can still stream video/audio or other files off the 2.5 though, so it doesn't bother me. Transfer speed is where I notice the difference mostly.

But yeah, my 3.5" never leaves the desk and my 2.5" has been halfway around the world hah. Soo each have their positives and negatives.

 

Portability and storage amount. I have a 3.5in at home for storage that isnt portable, and I have my 2.5in in my bag I take everywhere for storage on the go. The added feature of 2.5 is it is USB powered, whereas my 3.5 requires an outlet so trying to access data on the go is impossible without an outlet.

 

hello!! I just bought a Western Digital 160GB external hard drive for my Samsung Sens P55 notebook.. This is after I consulted with John Ratsey coz my laptop doesn't come with a recovery disk and there's no partition on my hard drive.. My reason for buying an external hard drive is to back up all my data incase my notebook encounters virus or glitches which in this highly technological advance world of ours is nothing short of a miracle... It works like a charm when transferring files but when I click the SAFELY REMOVE icon on the lower right of the screen to safely eject the external hard drive, I get this message: TROUBLE EJECTING USB.... TRY EJECTING LATER!! I did try ejecting it a couple of times but still it says the same thing... So I tried trouble shooting it but it all came out fine... So what I did was to turn off my laptop first, then after checking that the light on the external hard drive is turn off , that's the time I unplugged it... I returned the external hard drive back to the store where I bought it and explained what happen.. The store staff tried my external hard drive on their desktop and came out ok when clicking the SAFELY REMOVE ICON... (What the???) In view of the working SAFELY EJECT function in the store, they won't give me a replacement nor a refund... GGGRRR!!!! Right now I'm really confuse why my laptop won't recognize the SAFELY EJECT ICON when I plug in my external hard drive!!! But when I use other usb's like flashdrive, memory card, or even connecting my cellphone with a usb cable, the laptop recognizes the SAFELY REMOVE ICON and there's no problem ejecting it... I have 2 questions that I hope you tech guys can help answer:
1. Is my problem an isolated case or does this thing really happen? (OH WHY ME???)
2. Since I can't get a replacement and I'm stuck with this one, if my problem persist and my laptop won't recognize the SAFELY EJECT ICON, what should I do to SAFELY REMOVE MY EXTERNAL HARD DRIVE as not to subject it to an error or worse breakdown?
Thanks guys!!

 

ttl8me, if that external drive came with any kind of software which you allowed to be installed, then that is probably what is making your OS think it cannot let you remove it safely.