[Beowulf] Third-party drives not permitted on new Dell servers?

Lux, Jim (337C) james.p.lux at jpl.nasa.gov
Tue Feb 16 10:32:01 PST 2010

> -----Original Message-----
> From: beowulf-bounces at beowulf.org [mailto:beowulf-bounces at beowulf.org] On Behalf Of Rahul Nabar
> Sent: Tuesday, February 16, 2010 9:38 AM
> To: landman at scalableinformatics.com
> Cc: Mikhail Kuzminsky; beowulf at beowulf.org
> Subject: Re: [Beowulf] Third-party drives not permitted on new Dell servers?
> On Mon, Feb 15, 2010 at 7:41 PM, Joe Landman
> <landman at scalableinformatics.com> wrote:
> > Please indulge my taking a contrarian view based upon the products we
> > sell/support/ship.
> > I can't and won't sanction their tone to you ... they should have explained
> > things correctly.  Given that PERC are rebadged LSI, yeah, I know perfectly
> > well a whole mess of drives that *do not* work correctly with them.
> >
> > So please don't take Dell to task for trying to help you avoid making what
> > they consider a bad decision on specific components.  There could be a
> > marketing aspect to it, but support is a cost, and they want to minimize
> > costs.  Look at failure rates, and toss the suppliers who have very high
> > ones.
> Another worry is what happens in the long run if the vendor either
> folds shop or stops selling and / or supporting that particular model
> of drive. Frequently the lifecycle of these devices is longer than the
> warranty. The inability to shop around for drives could be  an issue.
> Especially with this rigid approach of firmware rejecting a foreign
> component and not just a warning.

"lifecycle" has a lot of meanings, and I think that's where the problems arise, in some cases.
For the most part, PC hardware these days is designed based on a 3 year replacement schedule, so a vendor will set up their warranty terms, model introduction and retirement schedule based on that, regardless of whether the actual life is much (sometimes much, much) longer (as all of us with old NT4.0 and DOS 3.x machines lurking in the lab know).

Unfortunately, the HPC (Beowulf) world is driven by the economics of the ordinary consumer/office desktop computer.  That's what lets you build a teraflop machine without incurring the debt of a small country: you can leverage the mass production for consumers which drives the prices down, but also has very short product cycles.

The 3 year cycle is driven by in large part by IRS depreciation rules which call computer equipment a "5-year" piece of gear, but MACRS means that by the end of year 3, you've already depreciated over 70% of the purchase price.  Considering that purchase price is about half the "total cost of ownership" (at most), it makes sense to buy new gear that often (since the help-desk, configuration management, networking, etc,  support costs remain fixed per month). The hardware cost is often a small fraction of the overall cost to put a computer on someone's desk. If you look at a typical desktop PC scenario, you might have a $2500 computer, where the first year depreciation is $42/mo, the second year is $67/mo, and the third year is $40/mo.  On top of that, support costs might be $100-200/mo.  In the fourth year, under MACRS, the depreciation is $24/mo.  So you could get a brand new computer (which will be easier to support, is faster, etc.) for a big $22/month hit on your budget(which is <10% of the total monthly tab, counting the support costs).  It's a no brainer to turn over the computers that fast, especially if you are trying to save on support costs by having a limited number of different models in the installed base at any given time (which is what large companies do).

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