OT probably, help please

[Dave Horsfall]

On Thu, 22 Jan 2015, William H. Magill wrote:

> After a tremendous amount of effort on the part of numerous kernel 
> programmers at DEC, they discovered that the bottom level BSD I/O 
> modules had not been "looked at" (literally) since PDP days. Disk I/O 
> was being done in 128 byte blocks.

You sure abut this?  My memory of the PDP days (ye olde 11/40) was that 
I/O was the same as the disk sector i.e. 512 bytes; this was V5/V6/V7 
Unix.

> One thing which I noticed immediately when I turned on iCloud disk in 
> Yosemite -- the "lag" involved with launching any program which stored 
> anything "in the cloud." Not unexpected, but significant none the less.

I've never bothered with iCloud; I don't store much stuff anyway (see my 
signature), and it all gets backed up to my Time Capsule.

> Similarly, I had a problem where my internal hard drive would literally 
> not spin-up. Took the iMac in to the Apple Store and they ran their 
> diagnostics and pronounced nothing wrong -- the tests passed with flying 
> colors!
> 
> I finally convinced them that the drive was not spinning up and they got 
> a tech to come out front who had a stethoscope and instantly verified 
> that the drive was not spinning.

Didn't they see the dreaded question mark on booting up?

> I've seen too many cases related to both BSD (and later Mach, i.e. NeXT 
> and OSX) where much of the hardware level "stuff" is completely ignored 
> by any of the upper-level reporting software. -- one of the main reasons 
> why Drive manufacturers developed S.M.A.R.T. -- the OS does not do the 
> job.

Hmmm...  I just tried SMART on my drive, but being an external USB drive 
(long story) it's not supported, so...

> In my experience, by the time the OS flags a Disk error, you have been 
> suffering constant performance degrading failures which are simply below 
> the "reporting threshold", for quite some time.

I have been seeing slow performance lately; I bought the MacBook early in 
2010, but it's a late 2009 model.  I wonder?

-- 
Dave Horsfall DTM (VK2KFU)  "Bliss is a MacBook with a FreeBSD server."
http://www.horsfall.org/spam.html (and check the home page whilst you're there)