Why do HDDs have standardized sizes?

[VirtualLarry]

Seems like that is one of the problems of leading to the commoditization of the HDD market. Why don't different mfgs come out with different, non-standard sizes, based on their internal platter densities? It would be harder to compare prices, if drive sizes were mfg-specific.

 

[taltamir]

it happens on occasion...

it is mostly a matter of "money spend on designing a drive model" vs "profit per increment in size".

You cannot just shove your best platter in all your drives and expect it to work.

For example, WD used 2x320GB platters (two double sided 160GB per side) for their WD 640GB and 320GB drives.

they decided to not spend the money and time to develop a 960GB drive, instead they first upgraded their platter tech to 333GB and then made a 3x 333GB = 1TB drive.

When they had that improved platter tech they did not go back and upgrade their 320GB single platter to a 333GB single platter and the 640GB double platter to a 777GB double platter because it was simply not worth the time and money to do so.

There are plenty of "higher priority" designs to finish first. at the time it was the 2TB 4x500GB platter... right now they are working on a 1x500GB platter design... it takes months of work to adapt the 500GB platter design in their 2TB drive to a single platter or even one sided platter (250GB) drive.

Another thing is... what is the difference between a 320GB and a 333GB platter? most likely? slight alterations to the MANUFACTURING devices to make it more "accurate", large alteration to drive internals (head size, accuracy, etc) and major modification to the firmware to make it USE the platter as a 333GB platter.
That is an oversimplification, but basically, the platters are not simple "plug and play" devices.

 

[tcsenter]

Originally posted by: VirtualLarry
Seems like that is one of the problems of leading to the commoditization of the HDD market. Why don't different mfgs come out with different, non-standard sizes, based on their internal platter densities? It would be harder to compare prices, if drive sizes were mfg-specific.

Do you really need someone to answer this for you?

 

[Idontcare]

Originally posted by: VirtualLarry
Seems like that is one of the problems of leading to the commoditization of the HDD market. Why don't different mfgs come out with different, non-standard sizes, based on their internal platter densities? It would be harder to compare prices, if drive sizes were mfg-specific.

Customer demographics really break down into two large categories - the folks like to buy at price-points (I budgeted $120 for my hdrive...what can I get?) and the folks who are looking to buy a certain capacity level (I want to upgrade to 1TB...how little can I spend to do this?).

As a supplier to a market with these dominate demographics the suppliers will naturally segment and cluster around specific capacities (1TB, 500GB, etc) as well as price tiers ($80, $100, $150, etc).

So why do hard drives have seemingly standardized capacities? Because competition forces the HDD makers to curry favor of the customer's preferences and this forces them to either evolve their capacities to near equivalent values (or risk losing sales if they are 5% too small or too large) or near equivalent pricepoints.

Supply and demand, of the demographic's preferences in this case.

 

[dac7nco]

Does this mean I'll soon be RAIDing a bunch of 4TB drives?!

 

[mikeford]

Size of a hard drive isn't written in stone, a decision is made on how much of the maximum track area to use, how much to allocate as spare sectors, and how much to leave as wasted space. The rest is marketing voodoo.

 

[Idontcare]

Originally posted by: mikeford
Size of a hard drive isn't written in stone, a decision is made on how much of the maximum track area to use, how much to allocate as spare sectors, and how much to leave as wasted space. The rest is marketing voodoo.

Yeah marketing voodoo for the first guy who releases the next "largest capacity drive in the world!"...but for the second, third, etc guys who are then following the lead the marketing voodoo reduces to "we need to match (or exceed by 1%) the lead guy's capacity".