Re: [mh] DIY Misterhouse Controller (embedded)

[John M. <jo...@wy...>]

A bad generalization on my part.

I should have been more specific - You are correct, they are not the same
drive.  Often times now, they are the same physical drive, with a different
configuration.  This configuration will be specific to the application.
I've built them.  They come off of the same lines, the differences are in
the quals, firmware configuration, and what will be covered in warranties.

Every manufacturer sells specialized drives for a variety of tasks - That
said, in many cases they are often virtually the same drive, with a
different firmware configuration, process, and limits.  Majior manufacturers
like seagate use desktop and notebook class drives to improve the margins on
their enterprise class drives...  The economies of scale are the driving
factor in a commodity item like hard drives.  The technology in modern
drives makes even 2-3 year old drives look ancient.

Modern notebook drives can last a long time in continuous duty - Often times
actuators designed for a raid system running slower, with less energy, will
run forever.  My laptop has been running since 95, as a linux server....
Not a production environment.

Either would be fine for misterhouse.






On Thu, Feb 12, 2009 at 7:44 AM, Joe Greco <jg...@ns...> wrote:

> > FWIW, almost all enterprise Raid/San drives being sold now are going to
> the
> > 2.5" notebook form factor, usually the same drives that are sold in
> laptops.
> > ;)
>
> Ah, ... no.  Not even anywhere near CLOSE to being true.
>
> The drives that are sold in laptops are designed for that use.
>
> For example, Seagate's laptop line is the Momentus.  You can find one of
> its data sheets at
>
> http://www.seagate.com/docs/pdf/datasheet/disc/ds_momentus_7200_4.pdf
>
> Take a careful look at the statistics, particularly the 350G operating
> and 1000G nonoperating shock rating, clearly designed for something that
> gets waved around while running.  Nice 1.5W power profile though :-)
> 600,000 load/unload cycles, and not an MTBF rating in sight.
>
> Now take a look at the Seagate Savvio, their enterprise class
> 2.5" drive:
>
> http://www.seagate.com/docs/pdf/datasheet/disc/ds_savvio_10k_3.pdf
>
> Now, note the 60G operating and 300G nonoperating shock rating, and
> the 3.5W idle running power.  The drive is a much higher performer.
> It is also intended for a 100% duty cycle.
>
> That means that you can smack a Momentus at 340G's *while it is
> running* and it's likely to still continue working, whereas such
> an impact to a *powered-down* Savvio is likely to damage or
> destroy it.  They are really *that* different.
>
> Just because two things happen to be the same form factor does not
> mean that they're the same type of thing.  The drives sold in a
> notebook are specifically designed for that task.  They are lower
> power, intended for many on/off cycles, rough(er) duty, but they
> offer lower performance as well.
>
> The server class drive, put in a notebook, would use more power, be
> less shock-resistant, generate more heat, and would probably survive
> a smaller number of on/off cycles.
>
> We don't put notebook-grade drives in a server, either, because they
> are simply not designed for always-on use.  The Soekris people have
> a page that talks about some specific exceptions, where a notebook
> drive has been designed for 100% duty cycles.  These drives are
> probably suitable for server work.
>
> http://wiki.soekris.info/What_2.5%22_hard_drives_are_suitable
>
> Hard drives have continued to specialize towards specific tasks, and
> while you may be able to take a server hard drive and stick it in a
> laptop, doing so comes at a cost.
>
> Picked correctly, a hard drive may treat you really well.  I've
> still got drives in production equipment that were manufactured in
> 1991, and have been run 100% duty cycle.  That's 18 years (and it
> amazes me).
>
> ... JG
> --
> Joe Greco - sol.net Network Services - Milwaukee, WI - http://www.sol.net
> "We call it the 'one bite at the apple' rule. Give me one chance [and] then
> I
> won't contact you again." - Direct Marketing Ass'n position on e-mail
> spam(CNN)
> With 24 million small businesses in the US alone, that's way too many
> apples.
>
>
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