Why must there be a actuator on a hard drive?

[Joe Auman]

The actuator is the last limitation in the speed of the hard drive. Why must there be only one? Two would be a problem. They could very easily smash into each other, unless they are on the opisite sides. But what if we removed it? How bout this. Lets say that the actuator reads using only one head that detects the magnetic charge of the platter below it. ok, now lets create one single, fixed, bar across the hard drive. That bar would house thousands of heads (a flood of new technology in the microdevices field would allow this), which could still acess each part of the hard drive, yet increase performance. How? Multiple file could be read at the same time without any part moving, except the platter. So, hundereds of files could be read/write at the same time with a increase in speed. Also, rotation speed could be increased even more to improve perofomance, so long as the platter and the bearings could handle it. Even multiple bars could be placed on the hard drive, and since the're fixed, they would never hurt anything. The only limitation is the interface and the software/hardware that could handle that much info at once. What do you guys think of this, a no-actuator hard drive? Or have someone already created this and I don't know about it? As always, correct me if I'm wrong and ignore me from my ramblings. This idea was bugging me for over a month and I have to see if it is possible.

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FATAL ERROR!!

Non-System brain or brain error!!
Replace and strike any key when ready.

[Toaster]

Joe,
Dual actuators are not new for HDD`s.
Back in the late 80`s to mid 90`s, mainframe HDD`s used dual "actuators" to reduce latency of head select time. The problem is that the actuator is a "precise" instrument and this drives up costs. With an add`l actuator, the needs for a duplicate actuator curcuit becomes necissary.
Older mainframe "storage assemblies" used a differing interface called IPI and SMD.
SMD is a close relative of ESDI and IPI is a relative (sorta) of SCSI.
Dual actuator drives are a thing to be "reborn" before long because of the following effects:
1. Seek times are halved in many cases.
2. Data rates nearly double.
3. Drive rotational speeds could be reduced and have no performance drawbacks thus reducing wear and increasing service life.
I used to convert IPI and SMD drives for large businesses to recoup the intitial cost of the drives.
While the drives never boasted large capacities like today, for their time they were huge and performed fantasticly.
These drives were typically 8 to 10 inch drives and there were 12 and 16 inch drives in very limited production.
My fav for converting was an HP-2021 "array" using the IPI interface. After conversion, the drives capacity was 2.44 GB and that was in early `91. These monsters were dumped in preference to SCSI and ESDI drives and became very cheap (3 cents per LB.). The conversion took some time and each time the drive worked flawlessly and performed exceptionately.
Most disk utilities of the era errored when accessing the drive due to its interface.
Typical seek times were 6.50ms and transfer rates were 20MB/sec on a "local bus" contoller.
This puppy was as large as a coffee table and created no dicernable noise other then a low fan noise. I`d love to do another using a PCI controller and a few mods I never got the chance to try.

[Joe Auman]

Thanks Toaster for that speedy and well informed response, but what do you think of my idea of a no-actuator hard drive? Possible?

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FATAL ERROR!!

Non-System brain or brain error!!
Replace and strike any key when ready.

[HAL9000]

If that's the case, why have a spinning platter at all.... we could call it a solid state drive http://www.pcmech.com/ubb/biggrin.gif

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If it ain't broke, you're not pushing hard enough!

[HAL9000]

What the matter Toaster? Don't have the huge bucks to buy solid state? http://www.pcmech.com/ubb/biggrin.gif

Just thought I would throw in that Seagate is going 15,000RPM on a new series of drives http://www.pcmech.com/ubb/eek.gif I still remember the first time I set up a server with 4 10,000RPM drives, the whine gave me a headache.... doesn't bother me now though. I can only imagine 4 15k drives spinning in harmony.

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If it ain't broke, you're not pushing hard enough!

[Toaster]

An actuator is the simplest and most cost efficient means to move the heads from track to track.
Solid state drives are common place but expensive.
Consider the cost of memory and then compute the cost of a 20 GB drive, the obvious will be quite clear.
Tests are being done with lasers and glass/plastic media but the "write" times exceed the "read" times by a factor of 3.
Mechanical actuators are quite hardy and serve purposes well and until drive capacities double (100-200 GB) then a change will have to be made due to track densities.
Mainstream HDD`s prolly wont change for the next 3-5 years just increase in capacities.
Interface problems will be the first bottleneck and then capacity issues.
Interface changes are being done and have been done for SCSI drives. Now there are FC-AL drives with data rates exceeding 100MB/sec and SCSI-160 with data rates exceeding 125MB/sec.
With mechanical actuators, about the "peak" access times will be about 7ms or so. This is about a reliable maximum.
Drive rotational speeds have exceeded 10k RPM for SCSI and this helps to some degree.
Seagate and Quantum both make 10K RPM drives and Fugitsu is prepping to produce a 12K RPM drive for SCSI-160 and FC-AL interfaces.

[Toaster]

Hal,
I thought I saw a reference to 15K drives but I seem to remember it was IBM. Seagate might be the one, they did it with the "cheetah" ,thier 10K drive.
I`m well aware what the older "Barracuda" drives sound like, I still have 4 that I stopped using.
Seagate even manufactured a 7200 full ht 32 GB SCSI drive but are nearly impossible to find. I`m not a seagate fan but thier full ht stuff is bullet proof and perform adaquately.
I saw a price on a "solid state" 2.5 GB drive. It was 688 bucks from quantum and is no longer produced due to heat problems and that it had a nasty habit of "forgetting". (really bad)
When they can make memory for pennies a MB, then things may change, don`t hold your breath.

[HAL9000]

You mentioned about running the 4 drives on one IDE cable. While I haven't tried 4, I did notice something interesting one day and have forgotten about it so haven't had a chance to persue it. It was at work when I was going to transfer some data to a couple of new drives with ghost. The version of ghost I was using had problems with drives 4.3Gb and larger, so I was doing some experimenting. I had two Quantum 4.3Gb hard drives. They were both on the secondary port, I cannot remember how they were jumpered. It might have been one as master, the other in the reserved position, or it may have been both in the reserved position. Anyway, to make a long story short, when I went into the BIOS to detect the drives, the secondary channel came up a single 8.6Gb drive on the master, and nothing on the slave. Unfortunately, I never had a chance to experiment with it more in depth that day, but now that you jogged my memory a bit Toaster... I gotta check that out again and load an OS and do a little benchmarking to see what happens.

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If it ain't broke, you're not pushing hard enough!

[HAL9000]

I quit holding my breath on stuff getting cheaper a long time ago.... doctor said I was losing to many brain cells and I needed a certain minimum to sustain life. I haven't been on IBM site for SCSI in a while, but I was on Seagates just yesterday checking specs for a customer and the 15k's were definitely listed on their site.

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If it ain't broke, you're not pushing hard enough!

[Toaster]

I understand about holding ones breath.
I`m from the "old school" and remember CLEARLY when 80MB drives were 1000 bucks and up. I still have my first HDD and controller combo from XT days. This HDD/controller combo normally retailed at 1100 bucks and I got it for 750 bucks when newer models began to come out. This was the ST-506 drive that boasted a whopping 5MB of storage and a MFM controller running at a 4:1 interleave. Data rates of this drive were a scalding 180KB/sec, below todays floppy rates. Now, one can buy 20GB drives for around the 100-120 mark that boast burst transfer rates of 16MB/sec or more.
With the cost of HDDs going thru the floor and performance creeping skyward, it wont be long that something will have to be done.
I saw on an obscure site in Australia where a couple of guys re-designed the IDE interface to handle 4 devices per port and also offered "combining" of all devices on a port. They were testing 4 20GB drives on one port that appeared to the O/S as one logical volume or 80GB. They claim performance double that of recent EIDE drives without loss of functionality or reliability. I`m trying to relocate this site as it was interesting and may bear fruit of their labors.
Iv`e tried "strapping" 2 SCSI drives and have limited sucess. My biggest drawback is how to enable cache on one drive and disable it on the other and then "switch" from one to another without the O/S getting wind of it.
I must of blown 20 EPROMS in trying to "reprogram" SCSI on the fly to achieve this.
This is the current state of my "old" barracuda drives. A few folks have "broke out" of the EIDE 80 pin interface to support 2 drives as one and one might expect a discovery in the coming months.
Many things are being tried but to date no real breakthroughs. Soon however, the PCI bus will become too slow for upcoming hardware and a change there will need to occur. To do this, the entire design of the PC would need to change.

[Toaster]

Hey Hal,
A few people have experienced what you have.
What they tried to do was set one drive to master, one slave and one on cable select.
As you suggested, these drives were also Quantum drives. I think there is somethin here but needs a lil research to hack out the weeds.
Its becoming obvious that folks dont like the "4" drive idea (2 per port)and they wish for support akin to SCSI.
Maybe a "universal" drive which adapts to a given interface?
Who knows but 1-2 years down the road may have some surprizes in store.

[shane254]

Use use something like a giant memory stick, but a 20 gig stick would put you back about 24 grand fast if you have the cash I think in about 10 years what we have now will be though of as junk in ten years hd will not have moving parts the will be a solid state like giant memory I wont be supprise if in ten years a 20 gig solid state drive will be the size of a stick of pc133 oh yea did I mention how fast it would be ohhhh ffaasstt

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Nothing is too fast!