[dennisgorelik]

1) Are you suggesting Standby server instead of SQL Server Cluster?

2) Another alternative could be RAID 1 or RAID 10. Catastrophic failure of two drives at once is extremely unlikely. Still there would be occasional maintenance downtime, but it looks like maintaining RAID solution would be easier than Stand By server.

[mechanical_fish]

RAID is a cheap answer but it doesn't solve the same problems. RAID controllers fail. Motherboards fail. Power supplies fail. Connectivity or power to entire racks fails.

Moreover, humans fail. RAID cannot save you from human error that corrupts the filesystem, for example. RAID is just a little too efficient at replicating changes from one drive to the other. There's a tradeoff between how up-to-date your mirror is and how much time you have to detect a problem on the primary and stop that problem from replicating to the slave; RAID is firmly parked on one edge of the space of solutions.

And, as you have noticed, RAID also cannot help you deploy your new code on one machine at a time, secure in the knowledge that you can fail over to the other machine in case of big trouble. (That doesn't work for every deployment, but it sure is a handy option when you need it.)

[hrasm]

My apologies. I misread the whole thing as a question about fault tolerance (which is not a bad thing to consider at all IMO). RAID will certainly help in your case. You need to come up with an estimate of how much your losses will be if you have a single point of failure. Usually, paid-for services have this factored into their pricing model.

But as another comment suggests, unless you are grumpy about Azure ToS or US laws (maybe Azure services exist outside the US) or whatever, you should take a look at Azure services.

[dennisgorelik]

Would Windows Azure allow me to avoid downtime during windows upgrades?