External HDD: 2,5" vs 3,5"

[Over]

I would like to know what are the advantages of 3,5" external drives, if you use them for storage purposes and compare same capacity drives (ex: 1TB for both 2,5 and 3.5").

 

3,5" external drivers are bigger, need a separate power supply, are little bit louder. I'm not sure, but I guess they can be faster? At least while I don't get USB3, I don't notice any differences between my WD 3,5" external drive and my WD Passport 2,5" external drive.

 

2,5" are smaller, quieter, only need to plug the USB cable. Maybe less RPM? As I said above, I don't notice any difference.

 

What am I missing here? I'm certainly missing something, or people would only be getting 2,5" external drives...

[Samdb]

If you get both the same RPM the 2.5" in theory should be faster because of the reduced surface area, but that is probably wrong, if not it will be a negligible amount.

[michaeldeve]

3.5" spins at a higher speed and can hold up to 4TB while 2.5" can hold up to a max of 1TB

[ThunderShark]

If they are the same capacity then there won't big a big difference. The main reason to get the 3.5" is that you can get them in higher capacities.

[alpenwasser]

If you get both the same RPM the 2.5" in theory should be faster because of the reduced surface area, but that is probably wrong, if not it will be a negligible amount.

Actually a 3.5" drive with identical rpm should be faster to some extent than a 2.5" one (provided

it actually uses 3.5" platters, there are 3.5" drives which use 2.5" platters, but those are 15k

drives I think).

Anyway, for the same rpm the outer part of the 3.5" platter will move faster in relation to the

read/write heads (since tangential velocity is dependent on radius), so provided the read/write

head can keep up with that higher velocity you should get faster read/write speeds, at least on

the outer areas of the platters.

This all assumes that the platters have the same information density of course. If the 2.5" drive

uses higher density platters then it can of course be faster than its 3.5" counterpart, or at least

come much closer, all else being equal. I'm not sure if that is common practice or not though.

As for the original question: 3.5" have higher capacities and usually lower cost per GB. 2.5"

drives are smaller, lighter, use less power and are often more resistant to shocks (since they

are often laptop drives which have been specifically engineered for such an environment).

[Samdb]

Actually a 3.5" drive with identical rpm should be faster to some extent than a 2.5" one (provided

it actually uses 3.5" platters, there are 3.5" drives which use 2.5" platters, but those are 15k

drives I think).

Anyway, for the same rpm the outer part of the 3.5" platter will move faster in relation to the

read/write heads (since tangential velocity is dependent on radius), so provided the read/write

head can keep up with that higher velocity you should get faster read/write speeds, at least on

the outer areas of the platters.

This all assumes that the platters have the same information density of course. If the 2.5" drive

uses higher density platters then it can of course be faster than its 3.5" counterpart, or at least

come much closer, all else being equal. I'm not sure if that is common practice or not though.

As for the original question: 3.5" have higher capacities and usually lower cost per GB. 2.5"

drives are smaller, lighter, use less power and are often more resistant to shocks (since they

are often laptop drives which have been specifically engineered for such an environment).

Well, you learn something new every day!

[_Vigo_]

I don't think that 3.5" external HDD would be much faster then 2.5" HDD in real world. 2.5" are smaller and for me it's more convenient to use it. 3.5" HDD is not fit in my pocket.

[Over]

Actually a 3.5" drive with identical rpm should be faster to some extent than a 2.5" one (provided

it actually uses 3.5" platters, there are 3.5" drives which use 2.5" platters, but those are 15k

drives I think).

Anyway, for the same rpm the outer part of the 3.5" platter will move faster in relation to the

read/write heads (since tangential velocity is dependent on radius), so provided the read/write

head can keep up with that higher velocity you should get faster read/write speeds, at least on

the outer areas of the platters.

This all assumes that the platters have the same information density of course. If the 2.5" drive

uses higher density platters then it can of course be faster than its 3.5" counterpart, or at least

come much closer, all else being equal. I'm not sure if that is common practice or not though.

As for the original question: 3.5" have higher capacities and usually lower cost per GB. 2.5"

drives are smaller, lighter, use less power and are often more resistant to shocks (since they

are often laptop drives which have been specifically engineered for such an environment).

 

So, 2,5" is better, unless price is the main factor in your purchase decision, right?

[Over]

3.5" spins at a higher speed and can hold up to 4TB while 2.5" can hold up to a max of 1TB

 

I just saw in a store today a Toshiba 2,5" external hard drive with 2TB capacity...

[michaeldeve]

I just saw in a store today a Toshiba 2,5" external hard drive with 2TB capacity...

Ok I did not know they got that big.

[alpenwasser]

Well, you learn something new every day!

 

 

I don't think that 3.5" external HDD would be much faster then 2.5" HDD in real world. 2.5" are smaller and for me it's more convenient to use it. 3.5" HDD is not fit in my pocket.

 

Yeah the 2.5" form factor is a lot more convenient to carry around, especially when you

consider that you often need an additional power brick for the 3.5" drives whereas the

2.5" drives can be powered via USB.

 

So, 2,5" is better, unless price is the main factor in your purchase decision, right?

Price or maximum capacity. But yes, in most cases I think a 2.5" is more convenient.

I just saw in a store today a Toshiba 2,5" external hard drive with 2TB capacity...

I think they're relatively new. Personally I would love for 2.5" to get more affordable

with regards to $/GB and replace my 3.5" drives with them. Less noise, less heat. But

that's a long way off.