Disk wear and tear 2

[xwb]

I don't know if I'm in the correct forum for this.

We have an application that runs on a server. This is the only application on the server. One thread writes files to a directory. Another thread copies them to another machine and deletes them. From what I can see, the files are always written to the same area of the disk. Sooner or later, that area of the disk will be unusable while the rest of the disk will be OK.

I was just wondering whether we should not delete any files until the free disk area gets down to 20%. That way more of the disk will get used and the disk might last longer.

Does anyone have any opinions on this?

 

[xwb]

what you mean by "locked us out"?

The actual geometry is hidden from us by the IDE interface. I haven't played with drive geometries since the early 90s. IDE is explained in

http://hem.passagen.se/communication/ide.html.

Even in the example, the drive geometry doesn't make sense. I don't think it is physically possible to put 16 heads on a drive that is 0.5" thick. It is just a device that you use. Doesn't matter if it tells white lies, as long as it works.

 

[LawnBoy]

It's been a long time since I studied drive geometries too.
<flashback to BCE>
The first hard drive I worked with was on a Johnson Controls HVAC system. It was 5 MB, and the size of a top-load deep freeze. The heads were FIXED; it had a huge drum for the platter that took upwards of 2 hours to come up to speed.
</flashback>


"We must fall back upon the old axiom that when all other contingencies fail, whatever remains, however improbable, must be the truth." - Sherlock Holmes

 

[edfair]

Up until IDE the controllers allowed a low level format of an indiviual track. You specified cylinder, head, and sector numbers into an image and told the system to write it. IDE drives don't do it.

The reality of the situation is that it isn't needed. There is no mis-alignment of heads and cylinders any more. They self adjust on the fly if all the parts are working.

Most of this stuff is hidden from us now by the operating systems. I got my education patching a dual SSSD floppy operating system to take other floppies and MFM hard drives using a SASI (precursor to SCSI) controller before IBM had hard drives on the PC.

Although I had been around hard drives for years as observer I didn't get hands on for the nitty-gritty until 1979. I think my favorite was the IBM with the 25 14" platters. This was probably a 24" by 24" by 72" glass encased cabinet with the upper half holding the platters and a common head stepping shaft moving the heads in unison.

Ed Fair
Give the wrong symptoms, get the wrong solutions.

 

[xwb]

You must have had gigantic muscles in those days. I remember carrying 2 of the 11 platter ones upstairs and having to put them in the top loading "washing machine". Didn't do your back any favours at all.

 

[wahnula]

This was probably a 24" by 24" by 72" glass encased cabinet with the upper half holding the platters and a common head stepping shaft moving the heads in unison.

I remember seeing those machines in TV ads for Control Data tech school in Miami, and my girlfriend worked for IBM in Boca and would constantly complain about those disks. I'll bet the performance of that rig is now bested by a handheld device...

Thanks for the clarification.

Tony

"If it can't take it, I don't want it

 

[edfair]

These were fixed disks. And thinking back (this was 45 years ago) the cabinet was more like 48" wide. If you moved it you got a moving company to do it. I don't remember ever hearing about a head crash on the one I saw but I can imagine the issue pulling the top 20 something platters off to get to one on the bottom.

 

[LawnBoy]

Hell my wristwatch has more capacity and performance...


"We must fall back upon the old axiom that when all other contingencies fail, whatever remains, however improbable, must be the truth." - Sherlock Holmes

 

[edfair]

Tony,
I needed some computer training so interviewed with Control Data to see if I could get IBM 1401 basics. They had the pretty pictures but the training was so general that it was worthless for what I needed. Their explanation was that the general information they taught qualified the student to be hired by a computer company where he would get specific training. The programming classes may have been OK but the hardware stuff was ripoff.

I would suspect that your girlfriend was griping about the 1316 or 2316 drive units. They were the washing machine style XWB described and more widely used.