Re: Striping data across platters in a single hard disk

On Fri, 06 Jan 2006 06:56:22 GMT, "tony" <tonynews@xxxxxxxxx> wrote:

>
>"George Macdonald" <fammacd=!SPAM^nothanks@xxxxxxxxxxxxx> wrote in message news:iv4rr1pefp8f4pokl505fmc90441uuqeim@xxxxxxxxxx
>> On Thu, 05 Jan 2006 02:51:46 GMT, "tony" <tonynews@xxxxxxxxx> wrote:
>>
>>>Why don't hard drive manufacturers figure out a way to
>>>stripe data across the multiple platters in a hard drive to
>>>get greater throughput? It seems to me that if you have
>>>multiple heads and platters you should be able to multiply
>>>the throughput to some extent based upon the number
>>>of heads/platters: a 2 platter drive should get almost twice
>>>the performance of a single platter drive. Why doesn't it
>>>work that way/how does it work?
>>
>> Well they used to do that when a single platter only held a few MBs (KBs if
>> you go back far enough) and spun at 3600rpm - don't recall if they went
>> slower but likely. With 160GB on a single platter now, you only need
>> multiple platters for huge drives or if you make a change in form factor.
>
>Or if it made doing the parallel head thing feasible (lower density makes the
>positioning thing easier?). Trade some capacity for higher throughput.

I think it'd be a *lot* of capcity from what I'm hearing from others.

>> It could also be that the more heads you have, the higher the chance of
>> mechanical failure - IOW aligning say 8 heads with 4 platters is very
>> difficult(?). The price of the on-board controllers is also orders of
>> magnitude lower than back in the old days so ganging a bunch separate
>> drives together in some kind of RAID formation is easy, cheap and
>> practical.
>
>It would take a lot of drives though to saturate a SATA II bus.
>
>I was at the Samsung site a few days ago and noticed that they are
>working on hybrid drives (flash mem + rotating media), but the mem
>part of it is only 1 GB so it seems more like a cache of sorts rather
>than general storage. I can't imagine that the hybrid drives will be
>cheap. If a single "striped" drive could be had for the price of a hybrid,
>that may be the acceptable price point to shoot for. Maybe getting multiple
>platter drives to produce higher throughput is wasted effort given the following
>technology:

I guess they have to have a market for all those flash chips they're
planning on producing... apart from Apple.:-)

>I read something about perpendicular magnetic platters. How about
>getting that to work in some kind of "parallel" fashion to increase throughput?

The only thing I've heard about "vertical" wrt disks is "vertical
recording" which has to do with the alignment of the magnetic particles on
the disk: instead of all lying side by side on the platter, they get stood
up on end - IOW it's about increased density. This has been talked about
for 20 years now and it's suddenly just starting to get implemented.

--
Rgds, George Macdonald
.

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