Re: Database design.

[Valdis.Kletnieks () vt edu]

On Tue, 06 Jun 2006 21:49:18 BST, Drsolly said:

> 300 gb drives cost about $100. You can put four of those in one computer, 
> total cost maybe $600. For 460 terabytes, you'd need some 400 of those, 
> which would cost $240,000.

Yeah, and that DMX3 quote would have been a lot cheaper if they'd just used
cheap $100 ATA drives, instead of the drives they actually use.  However,
when you're looking at 300 terabytes of disk, if you're using drives with
a 3-year MTBF like they use in the average consumer desktop, you're looking
at a failure *EVERY DAY* on the average.  Now the fun - even if you have a
hot spare that the array can rebuild onto, what is the probability that
(a) you'll have another drive fail before the rebuild finishes and (b) that
the 2nd failure is inside the rebuilding RAID set?

Hmmm.. let's see.  A petabyte would be about 3,000 drives, and a failure
every 8 hours.  Assuming you create 100 RAID sets of 30 drives each, and
you can rebuild a 30-drive RAID in 24 hours, you're looking at permanently
trashing a RAID set on the order of once or twice a year....  (You can
improve your chances by creating more RAID sets - but then you need to
allocate more hot spares....)

Attachment: _bin
Description:

_______________________________________________
Fun and Misc security discussion for OT posts.
https://linuxbox.org/cgi-bin/mailman/listinfo/funsec
Note: funsec is a public and open mailing list.