Why are there no 5.25" HDDs?

[dark_hag666]

As subject really....

i cant see arny reason why not. most if not all PCs have spare space for extra DVD drives. surely a 5.25" drive would have more width for each platter and more height to put maybe 2 more platters in.

maybe there are limitations like noise or a limit to spindle speeds

 

[Snapshot]

5.25" HDDs are the past. The first small (under 8") HDDs appeared in the '80s, around the time of the first IBM PCs and were 5.25", full height i.e. the size of two CD-ROM drives. These gradually shrank to half-height then the 3.5" half-height drives came in and finally we got the 3.5", 1" high drives we know today. A 5.25" drive would have much higher power consumption than a 3.5" as there would be much more metal to spin.

 

[rpstewart]

As above really.

I had a 5.25" Quantum Bigfoot a while back becuase it was the cheapest way of getting a huge disk at the time - all 2.5Gb of it I can also remember using a machine with a 330Mb ESDI full height drive, that thing was the size of a small shoe box.

While a 5" platter drive with current technology would give huge capacities per platter and tremendous speed at the outer edge there are difficulties in doing it. The heat generation alone would be huge, the bulk of heat in HDDs comes from air friction caused by the spinning platters, 5" platters would generate a huge amount more than 3.5"HDDs (Raptors and most SCSI drives use 2.5" rather than 3.x" platters for this reason). There may be other issues with head placement accuracy due to the larger throw but I've no idea if that would be the case.

The biggest detractor though I think would be the lack of market. Most home/office PCs wouldn't be able to take a 5.25" HDD due to the small form factor of their cases. Plus is there a desire in the market place for 2Tb+ single spindle HDDs? I don't think there is, if you look about here there aren't that many of us who are running more than 1Tb and those who are have RAID arrays, backup drives etc rather than a bunch of drives all containing unique data.

As a technical exercise I'd like to see it done though, it's the only chance really to approach the capacity of HDD interfaces with a mechanical disk, in reality however I doubt it'll happen.

 

[Snapshot]

Ah yes, the Bigfoot. Dog slow IIRC and probably the last 5.25" HDD.
I built my first PC almost 17 years ago. It was a 386SX/16 with 2 f/h 5.25" 68MB HDDs, built so I could multi-task using DesQview. We've moved on a bit since then....

 

[rpstewart]

Ah yes, the Bigfoot. Dog slow IIRC and probably the last 5.25" HDD.

Yup slower than a sloth in treacle but half the price of anything of comparable size.

I built my first PC almost 17 years ago. It was a 386SX/16 with 2 f/h 5.25" 68MB HDDs, built so I could multi-task using DesQview. We've moved on a bit since then....

By 'eck lad that takes me back... That sounds like quite a machine for the day, I though I was the bees knees with a 43Mb disk at that time!

 

[squiffy]

My 286 12mhz had a 320MB SCSI hard drive! At the time only 40MB IDE hard drives were out, and they were still very expensive! Got some ESDI 10MB 5.25" full height drives around here somewhere

 

[Snapshot]

By 'eck lad that takes me back... That sounds like quite a machine for the day, I though I was the bees knees with a 43Mb disk at that time!

I was very lucky as the 68MB drives were left over when we upgraded some of our clients' mini-computers* to SCSI drives. The clients didn't want them and there was no mechanism for putting them back into stores. Quite a few of us in Engineering benefited from this.


*Wang VS5 & 6 for anyone who might remember them.

 

[dark_hag666]

As above really.

I had a 5.25" Quantum Bigfoot a while back becuase it was the cheapest way of getting a huge disk at the time - all 2.5Gb of it I can also remember using a machine with a 330Mb ESDI full height drive, that thing was the size of a small shoe box.

While a 5" platter drive with current technology would give huge capacities per platter and tremendous speed at the outer edge there are difficulties in doing it. The heat generation alone would be huge, the bulk of heat in HDDs comes from air friction caused by the spinning platters, 5" platters would generate a huge amount more than 3.5"HDDs (Raptors and most SCSI drives use 2.5" rather than 3.x" platters for this reason). There may be other issues with head placement accuracy due to the larger throw but I've no idea if that would be the case.

The biggest detractor though I think would be the lack of market. Most home/office PCs wouldn't be able to take a 5.25" HDD due to the small form factor of their cases. Plus is there a desire in the market place for 2Tb+ single spindle HDDs? I don't think there is, if you look about here there aren't that many of us who are running more than 1Tb and those who are have RAID arrays, backup drives etc rather than a bunch of drives all containing unique data.

As a technical exercise I'd like to see it done though, it's the only chance really to approach the capacity of HDD interfaces with a mechanical disk, in reality however I doubt it'll happen.

Thanks, although I dont agree with argument that theres no market for it. 2 years ago was there a market for 1Tb? I'd say now is the best time for it, with TV shows and movie downloads hitting the legal mainstream.

Also, if the air friction is a problem then i could be manufatured in a lower friction gas like Helium. I also can't see size as a problem, obviously width isnt, the height wouldn't have the be bigger than current drives (if it have the same number of platters) and i can see why th length would be greater than a DVD drive. Most PCs had at least 1 free 5.25" drive space.

But then I'm no electrical Engineer, just an ex-Product design student with a dream

 

[Justintime]

Access, seek time etc.. would go up a lot with a bigger hard disk platter and thus performance would suffer, remember the heads have a lot more to travel with a 5.25 platter than it would with a 3.5 etc.. This is why the Quantum Bigfoot had a miserable rep of being a sloth.