why don't anybody ever make 5.25'' hard drives?

[lee1026]

It makes perfect sense to do that because 3.5'' hard drives are already designed for the disktop - no problem with space involved. also cases have to be at least 5.25'' wide anyway, thanks to the CDs/DVDs. wouldn't it be better to make HDs also 5.25? after all, the platters would be much bigger and so I would imagine that read times as well as size would improve dramatically, wouldn't it?

[Snugglebear]

There was a time when disk packs were the size of washing machines and the disks platters themselves dwarfed dinner plates. Programmers accessed these devices at the lowest of levels, meaning you controlled the movement of the disk arms themselves. A couple of my old professors discovered late one night in the labs that if you wrote a program to perform a specific series of disk accesses, the packs would jump out of place. After that they used to hold late night competitions - disk pack races - where they'd see who could write a program to make their pack jiggle a few feet to the finish line the fastest. I had the fortune of seeing a disk pack walk back in undergrad, but unfortunately it was the only one left, so we could not race them.

That's something of a tangent, but it is related to the overall point here. Larger platters have higher masses than their smaller counterparts. More mass means more energy is required to spin them up, more vibration (noise) is produced, more heat is produced, balance is harder produce and maintain, and the outer edges are moving at very high linear velocities. Likewise, the disk arms themselves have to travel even farther distances and yet will also mass more, requiring larger actuators, more energy to move, higher speeds to transition the larger distances in similar times, and more time to accelerate and decelerate. All this means that the larger drive is going to be louder, hotter, consume more power, be more prone to catastrophic failure, and have far higher seek times. These problems could be dealt with by lowering rotational speeds, but then that would eliminate the sequential transfer speed advantage.

There are two other large problems here that are also worth mentioning. First, bigger drives cost more to manufacture, and given the margins the drive mfgs are working with, that's a very bad move for them. Secondly, as one increases the size of platters or increases the areal density, seek times go up due to the likelihood of missing your access window. Essentially more and more bits are flying by in a given timeframe and it becomes much harder to finish up reading/writing one sector and moving the head to the next before the bits you want cruise by and we're stuck waiting for the next rotation. This is one of the main reasons that seek times aren't going down as drives get larger and larger, in fact many are going up slightly.

In the end, the trend is towards smaller form factors and platter sizes. Increases in areal density mean more bits can be packed on smaller spaces. This allows platters to shrink in size yet maintain or even grow in overall storage capacity. Smaller platters mean less heat, less energy, less noise, and lower seek times due to smaller distances being involved. Manufacturers can then do something else, raise the rotational velocity and provide us storage snobs with our 15,000 RPM drives and beyond. Trends in general IT are very similar, with most corporations attempting to massively increase computing densities; we're cramming more and more computers into smaller form factors and still expecting them to be better performing and larger capacity than the systems they replace. These two forces are combining to see manufacturers like Seagate develop products like the Savvio, which are 2.5" form factor drives. They perform just as well as 3.5" units, but are smaller, cooler, and cheaper to manufacture. All that leaves the big drives destined for museums.

[Showstoppermd]

Bigfoot = yuck !!

[JTanczos]

I remember my old 20mg hard drives in my dads 286 that were 5½".

I wondered why they didnt go back up either but I guess now we know! Have to wait until the bits get perpendicular. :D
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JT

[ghettocomp]

I used to have a Bigfoot drive. nasty, strange drive... only worked at certain temps as well.

Nostalgia kicks in.... Used to work with a Sperry-Univac system with 20" removable drives...


Edit: Might be wrong on the 20" part but the size is very close..BIG..

[shellshock]

With smaller platters, you can spin them much faster than having huge ones, and plus, smaller platters are much more reliable than there larger counterparts. For example, look at the size of the platters on the raptor, there smaller than our standard 7200 drives

[LoneWolf121188]

Bigfoot = yuck !!
Ahh, yes, the bigfoot. I had one of those for a while. I gave that whole comp to a friend a few years back. I think it was an IBM Aptiva, under 400MHz, maybe 8GB of HDD...

[ocminimus]

I imagine in 2-3 years you will be able to pack most everything you need into much smaller cases. Big..bulky...loud. Always moving towards being a thing of the past.

[LoneWolf121188]

I imagine in 2-3 years you will be able to pack most everything you need into much smaller cases. Big..bulky...loud. Always moving towards being a thing of the past.
three things prevent things from getting smaller: The size of your hands/fingers (for manupulating components), heat (and the means to dissapate it), and...I forget what the third one was... :bang head agh! I had it! Hang on, it'll come back to me...

[Veland]

Wasn't the bigfoot actually a cheap drive? I seem to remember it as a "value" drive. Guess it was because large/cheap component's could be used..

Also, large platters would mean a bigger difference between where on the drive files are stored since the velocity would be very different!