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Re: SuperMicro H8SSL-i (ServerWorks HT1000) -- providing technical information

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Mark Hahn <hahn@xxxxxxxxxxxxxxxxxxx> wrote:
> arrg!  this is the sort of thing that gets my goat - you
> claim that if the capacity and performance numbers match,
> then the only difference between the drives must be some
> sort of "enterprise" testing.  but without hard facts from
> the vendor, this is just speculation on your part.  sure,
> it could make sense, and might even make Occam happy.  but
> not QED, still speculation.

It first started almost 3 years ago I read an article in
StorageReview (IIRC) about the coming "near-line" enterprise
disk.  They interviewed the [former] Quantum product line
manager and talked about the process in which they test their
commodity capacities for tolerances.  They then set aside the
units for different warranty and packaging.  At first, they
just did it for integrators and VARs -- non-desktop OEM uses.
 He was talking about the "critical mass" of this, as more
and more vendors were not happy with what the enterprise
capacities were delivering, and that was driving the new
model.

Since then I've talked to product managers at Seagate and
Hitachi.  They both told me how all of the products roll of
the same mechanics line, except for the traditional
enterprise capacities, which are clearly fabbed with far
greater precision and better materials.

In talking to the Seagate rep about the new 60C tolerance
process, he explicitly told me that their forthcoming (at the
time) NL35 line was rolling off the same line as those
destined for the 7200.7 and, forthcoming, 7200.8.  Hitachi
has made similar statements with regards to their product
lines.

Most people don't know that Hitachi fabs many of Western
Digital's drives, which was previously done by IBM before
they sold to Hitachi GST.  I'm not sure who Western Digital
is using for some of their newer models though.

> translation: some disks have MTBF of X and capacity of C.
> this other disk has capacity C, therefore it has MTBF of X.

My point _continues_ to be that if an "enterprise rated"
drive of commodity 100-400GB capacity is 1.0M hours MTBF,
then there's _no_way_ a standard OEM/desktop version could be
even 1.0M hours MTBF.  That's _all_ my point was.

It is very safe to assume it's still 0.4M hours (50,000
restarts @ 8 hours/day) MTBF and remains unchanged.  In the
"best case" you could even say maybe 0.6-0.7M hours MTBF.  Do
*NOT* expect >1.0M hours MTBF with these drives.

Lastly, "real world" experience in just the last year at 2
major Fortune 100 companies with thousands of desktops has
shown that OEM/desktop products have failure rates _much_,
_much_ higher!  ;->

> why does "rest assured" always mean "I say"?

If you have anything to contribute other than to be negative
and dismiss the references and logical presentation of all
this, then please do.  I'm sorry I can't give you the
absolute exact answer you want, but I have presented
technical information with exacting vendor documents that do
as best as I can, and everything else is logical presentation
of those facts.

If you are wanting me to point to some vendor's documentation
that says, "yes, our drives suck -- we're not even making our
MTBFs on OEM/desktop units anymore, so we don't even bother
publishing them" -- sorry, not going to obviously happen. 
;->

> 8, 14, who's counting?  do you have any real backup for the
> claim (afaikt) that reliability is strictly a function of
> power cycles?

After IBM put 5 platters in its infamous 75GXP (something
Hitachi recently did in its new 500GB version -- stupid
IMHO), there was a number of storage articles on all this. 
IBM went so far as to putting a "hard" warranty limitation on
usage over 14x5.  Now I seriously doubt that IBM could
enforce that on end-users, but it surely did on OEMs --
especially integrators.

That's really the "apex" of all this, almost economics at
work.  At 75GB, commodity capacity clearly overtook
enterprise significantly.  Furthermore, with the massive
sales of more and more desktops than total in servers, and
the emergence of ATA as an option more and more took -- even
the low-cost, low-margin of commodity disk offered a volume
that was too great to ignore.

So, again, as more and more server OEMs and integrators
looked to commodity capacities for 24x7 network-managed use,
the manufacturers started offering the options.  You can't
get the capacities you want in a truly enterprise-quality
fabricated disk -- the mechanics are far more exacting, the
materials far more costly.

> what if you put a "desktop" drive into a nice rack-mounted,
> UPS-protected, machineroom at a constant 20C with great
> airflow?  I've got a bunch of servers (netboot but swap and
> /tmp on local disks) that have been in use for ~3 years and
> smartctl tells me the disks have seen ~100 power cycles.

It's more than just heat.

The new materials now raise the ambient tolerance of
commodity disks to 60C from the traditional 40C -- far more
in-line with traditional 55C enterprise tolerances.

Vibration of the higher capacity platters is a serious issue.
 Something that vendors have to be more exacting on when they
deal with 10+Krpm disks, but not so much on commodity
7200rpm.

And then there's the materials -- from bearings to lube
choice.  From my understanding, that's the big cost factor
there.  One that really makes the cost prohibitive for those
looking for the GB/$, whereas those who want it are willing
to pay more ($) for less (GB).

> warranties typically just say something weaselish like
> "does not cover abuse".  how would a vendor refuse warranty
> replacement because of 24x7?  would they just run SMART and

> divide POH by power cycle count?

How many times do I have to say this.

I agreed that manufacturers/vendors can't do much about
end-users.  If you want to go with the Western Digital Caviar
SE instead of the RE, or the Seagate Barracuda 7200.x instead
of the Seagate NL35, then go for it!  If the same
"enterprise" versions of these capacities are rated for 1.0M
hours MTBF, then I don't know what you expect out of the
"regular" versions.

*BUT* if a OEM or integrator is selling a 24x7 server or 24x7
network-managed product with its drives, then they can hold
them to such.  They can _void_ warranty because of the
application which the drive is not warrantied for -- quickly
citeable in the OEM/integrators application specificatons. 
That's the issue, and the reason for products such as the
Seagate NL35, Western Digital Caviar RE, etc...

> oh, no!  I've abused node2's disk by averaging 289 hours
> per cycle! (interestingly, current temp is 26C, lifetime
> min/max is 13/36.)

And that's your choice.

I'm just stating what you want, how many hours MTBF you can
expect to get out of the drives you are using.

> so far, I'm not sure you've done anything to earn anyone's
> trust on, for instance, the 50,000 * 8 hours => 400Khour
MTBF
> assertion.  repeating it for years won't help...

I sincerely hope you can take _all_ of the technical
information and insight I have provided at my time and
literally years of research and interviews with industry
employees and appreciate it in the context it was presented.

Otherwise, I don't know what to tell you.


-- 
Bryan J. Smith                | Sent from Yahoo Mail
mailto:b.j.smith@xxxxxxxx     |  (please excuse any
http://thebs413.blogspot.com/ |   missing headers)

-- 

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