On Mon, 2009-01-26 at 08:53 -0500, erik quanstrom wrote: > > 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?
Yes. See here for details: http://blogs.sun.com/bonwick/entry/raid_z > > > 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. Then, please, restate it. > 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. Only if you asked for that to happen. Its all under your control. You may decide to never ever do scrubbing. > > 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. You may think what you want, but obviously quite a few existing small to mid-size companies disagree. Including a couple of labs with MPI apps now running on EC2. May be your numbers are wrong, may be your usage patterns are different. Who knows. Thanks, Roman.
