On Thu, Apr 14, 2011 at 12:27:34PM -0600, Scott Marlowe wrote:
> > That's what a UPS and genset are for. Who writes critical stuff to *any*
> > drive without power backup?
>
> Because power supply systems with UPS never fail.
Right, there's obviously a trade-off here. Some of this has to do
with how much your data is worth vs. how much the speed is worth.
There's also the issue of whether you can stand to lose a few rows,
and whether you can stand to lose them for a short time. For
instance, collecting user comments might be a matter of great value,
but if you write them to more than one system, you might not care
whether one of the systems fails briefly. In that case, maybe big
redundancy of cheap disks with power backup is good enough to meet the
price:value ratio. On stock trades worth maybe millions of dollars,
not so much: you miss your teeny window of opportunity to do a trade
and suddenly you're out in the street wearing a barrel.
I can think of lots of different points to be along that continuum,
and surely nobody is suggesting that there is one right answer for
everything.
A
--
Andrew Sullivan
ajs@crankycanuck.ca
