Re: NT vs AS/400

With all the claims & counter claims flying back & forth, I have not seen
any real presentation of real statistics to back up either claim. Somewhere
deep with IBM I know they exist, and IBM does make many announcements about
the reliability of the AS400 hardware & microcode. I DO beleive the iSeries
is far more reliable than NT (an operating system, not hardware)servers,
even the IBM servers. I have worked in several large shops, with over a
hundred as400s, and many NT's (Compaq and IBM, and over a thousand pc's. It
was like nite & day. The 400 disk drive problems (very few in many years)
were usually if the ups was not connected right. Even when properly power
protected, the NT's suffered many disk problems. If there were 2-3 disk
problems with over a hundred as400's, we had 5 times that in the NT servers
and 10 times that in desktop disk problems. In all cases the 400 drives were
"pumped".
Not truly statistical, but I have seen the same pattern in every shop I've
worked in. I don't need no stinkin' study to tell me the iSeries400 hardware
is far more reliable. I would gladly pay a premium for that.
jim

----- Original Message -----
From: "John Taylor" <john.taylor@telusplanet.net>
To: <MIDRANGE-L@midrange.com>
Sent: Saturday, June 02, 2001 1:58 PM
Subject: Re: NT vs AS/400


> Neil,
>
> You're right when you say that the drive consists of more than an
enclosure.
> Specifically, a hard drive consists of the following within the enclosure:
>
> -disk platters
> -spindle shaft & motor
> -read/write heads & armatures
> -actuator
> -preamp circuitry
> -air filter & pressure vent
>
> These are the most costly components of the drive, and are identical
across
> the various interfaces (IDE, SCSI etc).
>
> Attached to the outside of the enclosure of all modern drives is a printed
> circuit board (PCB) that provides the electronics necessary for physical
> control of the motors. The PCB also hosts the physical interface,
> configuration switches, and a controller chip.
>
> The controller chip on drives destined for the AS/400 production line are
> likely modified, but my guess is that this is limited to embedding some
kind
> of an ID that is recognized by the SLIC, in order to lock us into using
only
> those drives sold for the AS/400. The fact that you can get an AS/400
drive
> working in a PC with a SCSI subsystem supports my conclusion.
>
> Moving right along, let's address the often touted advantages of those
> special AS/400 drives. Specifically, I'll address the ones you mentioned:
>
> 1) Predictive failure analysis
>
> This is not exclusive to the AS/400, nor has it ever been. Please consult
> the following references:
>
> http://www.storage.ibm.com/oem/tech/pfa.htm
> http://www.storage.ibm.com/hardsoft/diskdrdl/ultra/ul73lzx.htm
>
> The advantage for the AS/400 is that the SLIC and OS/400 directly react to
> the drive feedback. On xSeries machines running NT/W2K/Linux, there are
> separate software applications to handle this. The software is usually
model
> & OS dependent. In the case of my Netfinity/NT boxes, this package is
called
> the Netfinity Service Manager.
>
> 2) Better reliability
>
> Hard disk reliability is measure by MTBF, and is most often determined by
> the quality of components and operating environment. It's the stuff inside
> the enclosure that usually fail, not the PCB. Reliability problems caused
by
> microcode generally show up early, cause consistent problems, and are
> addressed by installing a fix.
>
> I've installed microcode fixes for the SCSI drives on our Netfinity, and
for
> the IDE drives in our workstation. There is nothing magical about this
that
> is exclusive to an AS/400. Of course, IBM written microcode is not going
to
> work on a BCC drive, and BCC can't upgrade the drive controller through
> OS/400 & SLIC, so that's a definite problem with 3rd-party drives on
AS/400.
>
> 3) AS/400 IOP's
>
> How a hard drive comminicates with a processor is referred to as "Transfer
> Protocal". There are two types of transfer protocals; PIO Mode (Programmed
> I/O), and DMA (Direct Memory Access). SCSI drives use PIO mode to talk to
a
> processor. The operative word here is *a* processor. They neither know,
nor
> care that the processor in question happens to be an IOP instead of the
main
> CPU.
>
>
> After the last few days of participating in this thread, I'm probably
> beginning to sound like a mischiefmaker who's only interest is stirring
the
> pot. That's not entirely true. I *am* trying to stir the pot, but my goal
is
> simply to challenge the erroneous claims that are routinely made to defend
> the business practices of IBM. This strategy of blind loyalty to the brand
> and summary dismissal of anything not born in Rochester, is akin to
sticking
> one's head in the sand to evade a predator. More importantly, when it
> includes the use of half-truths and otherwise misleading information in
the
> message, it only serves to discredit the messenger, and his campaign.
>
>
> John Taylor
> Canada
>
> p.s. Neil, this was a general rant, and in no way directed at your
> personally.
>
>
>
> ----- Original Message -----
> From: "Neil Palmer" <neilp@dpslink.com>
> To: <MIDRANGE-L@midrange.com>
> Sent: Saturday, June 02, 2001 09:51
> Subject: Re: NT vs AS/400
>
>
> > Not that it justifies the entire price difference, but you are not
> > comparing apples with apples here.  There's more to the disk unit than
the
> > base disk enclosure.  Rochester adds the controller & microcode to those
> > drives (what gives it better reliability, predictive failure analysis
> > capabilities, and ability to work with the IO processors).  There is
> > obviously some overhead costs associated with that work that are added
to
> > the price of the disk unit.  (And when you buy 3rd party disk like BCC
you
> > don't get those controllers or microcode, which is why some disk related
> > PTF's won't work with non-IBM disk, and in fact could cause problems).
> >
> > ...Neil
> >
>
>
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