Re: [9fans] Changelogs & Patches?

[erik quanstrom <quanstro@quanstro.net>]

> It depends on the vdev configuration. You can do simple mirroring
> or you can do RAID-Z (which is more or less RAID-5 done properly).

"raid5 done properly"?  could you back up this claim?

also, with services like ec2, it's no use doing raid since all
your data could be on the same drive, regardless what the tell
you.

> > does this depend on the amount of i/o one does on the data or does
> > zfs scrub at a minimum rate anyway.  if it does, that would be expensive.
>
> You can do resilvering (fixing the data that is known to be
> bad) or scrubbing (verifying and fixing *all* the data). You
> also can configure things so that bad blocks either trigger
> or don't automatic resilvering. Does this answer your question?

no.  not at all.  if you're serious about using ec2, one of the
costs you need to control is your b/w usage.  you're going to
notice overly-aggressive scrubbing in your mothly bill.

> > maybe ec2 is heads amazon wins, tails you loose?
>
> The scariest takeaway from the conference was: with the economy
> the way it is physical on-site datacenters are becoming a
> luxury for all but the most wealthy companies. Thus whether
> we like it or not virtual data centers are here to stay.

if the numbers i came up with for coraid are correct, it would would cost
coraid about 50x more to use ec2.  that is, if we can run plan 9
at all.

- erik