🚀 go-pugleaf

In article <40to34$4lc@aurora.cs.athabascau.ca>,
Ross Alexander <rwa@cs.athabascau.ca> wrote:
>cis115@ws001a.cis.squared.com (Tony Gast) writes:
>
>
>BTW, all the business of just how wonderful your UPS safeguards are is
>beside the point; what if the failure is in the cache RAM parts
>themselves, or their controller, or the raid box's backplane, or the
>scsi disk controller that ties to the disks proper?  Power outage
>isn't the only failure mode on the planet.

  The failure of an add on UPS, due to component failure is
much worse than a failure of an integrated backup component.
If the system integrity is dependent on plugging into a ups
then that is very bad.  The possibility of a failure due to
failure of the interconnect would be high, since there would
be no redundancy possible, the simplest way to enhance the 
situation.

I would assume that the SC Raid 7 has redundant supplies etc
to reduce vulnerability to that, I have seen that they have
non volatile ram to be completely sure.

I therefore don't think that the chances of failure are any
greater than what is induced via the overall greater complexity
of the system. 

  SC has stated that they use non volatile add in PCMCIA's which is
pretty clever to back up the data, and I would hope that they must
be added in 2's 3's or 5's to ensure that the data is non volatile.

  You really can't do any better WRT component failure factors between
a "ordinary" raid vs a Raid 7, because you have just about the same
number of components (let's say the only difference is the buffer
modules).  Let's assume they have nearly the same number of components
other than the memories If either of the 2 components added (the
buffers) fail, you won't loose data.

  A reliability study would see no difference between them.
>
>regards,
>Ross
>--
>Ross Alexander, ve6pdq  --  (403) 675 6311  --  rwa@cs.athabascau.ca


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Jim Stephens    jws@world.std.com                Irvine, Ca
url *new* http://www.realm.net/~jws
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