Brad, you misunderstanding how backups are done. You seem to think that offsite backups are not subject to virus attacks and such and that is not true. Any backup in the world could be hacked while the backup is taking place. The backup unit can fail while the backup is taking place.
RAID is a configuration, nothing more. It is a way of setting up multiple disks, You ask how I can fail to see your point but you are missing the entire point. The point is, what media do you put the backups on? THAT is the point. And I tell you, most backups are going to be done on hard disks. Hard disks which are set up in a raid format to allow duplication of the backup. Raid has NOTHING to do with virus or hacking, THAT is the server itself that is being communicated with for the offsite backup. If that server were to get a virus or get hacked, NO backup is going to succeed, that includes optical, tape OR flash ram.
Bottom line is raid is just a WAY to setup hard drives to be used. That's it. It does not do anything else. It only saves data, nothing else. Everything else is controlled by the OS it is hooked to.
So are you trying to tell me that if you save data to 2 or more hard drives and ONE fails, that ALL the data is gone?
Of course not. The other disk(s) still have that data.
Also, most companies maintain running raids that are constantly backing things up while offsite is usually done one or twice a day , some might do it more but it is not constant. It is done during lulls in network traffic.
I never said using hard discs for backup was a bad choice. I said RAID is not a backup. Distinctly different. If you rely solely on your single live vulnerable copy you are doing it wrong. And this is all RAID provides on it's own. Great for high availability, horrible for long term data safety.
Proper backup techniques DO protect you from Malicious software and activities because if you are doing it right you will have a backup of the data PRIOR to the loss/compromisation. RAID will never provide this on its own. You need something disconnected from the live system to consider that data safe. Hard drives can be that media, but you won't be using two hard drives mirrored as the technique.
Yes, backups can fail. You could be hacked while a backup was occurring. But will that affect your previous backup? Nope. You're still okay. You might not save ALL your data, but you can save the majority of it. That's what you're trying to do. If you put all your eggs in two cartons but still the same basket (RAID) you can lose all of them in one swoop.
My point on the mirror RAID was this: Lets say you have a basic two-mirrored 1TB hard drive array full to the gills and one drive fails. Yes, your data is still 'safe'. But now you are tasked with re-mirroring that entire dataset. What makes you think you are at near-zero risk of that drive failing during re-mirroring? If it does, poof, all your data is gone excepting a data recovery service, etc. Now lets assume a massive kernel level failure completely overwrites ALL the data on the RAID array. Poof! Everything is gone. Now lets assume somebody wanted to deliberately wipe out your data, knowing you had no backups because your company was a failure of life. Goodbye data. Next thugs break in and haul off your equipment...
Will you STILL argue that RAID is a proper backup solution? That covers all possible data failure modes?
If you have no true backups you are now screwed. And that is one reason why sequential, off-system backups are important. And any company that has to maintain a high level of data integrity WILL use some method of ensuring they have secure, off-system backups of any critical data. If your company doesn't it probably has more to do with the fact that your data is not critical than the technique in use being a good idea. I work with medical records, where a persons life can depend on high availability and integrity of the data. And a hospitals reputation can depend on the integrity and security of the medical record data...
Please, if you are at all responsible for the data integrity of anything important. Do yourself a favor, pull your head out of your behind and start by googling "Raid is not a backup". While 90% of what I just said doesn't apply to the starter of this thread (my apologies for spamming it with my preaching), it's irresponsible of you to spout completely false information.
Saying RAID is a backup is like saying a crecent wrench is the proper tool to loosen bolts. Sure, it's more convenient most of the time and saves you the trouble and expense of having to actually go find, buy and use the proper tool... but every once in a while you'll find yourself screwed...
Good choice, since you can't get Chlordane anymore... 
on the serious side, someone said they don't use CDs or DVDs for backup because they don't last forever? They only degrade thru usage (unless you leave them sitting in the sun, or otherwise improperly stored) and if their primary use is backup, they shouldn't be getting used much and should certainly out live your grandchildren in terms of being able to recover data. Now magnetic media...yeah, that's why it isn't used much any more, except for tapes, and those are primarily used for short term backups. If you really feel insecure about losing a CD , make 2 or 3 copies. They're a whole lot cheaper than another HDD. I think we're getting lost in the semantics..RAID is NOT backup, yes it's true your data is "backed up" on some other part of the RAID but, it is a loss prevention system. You cannot recover your data if someone steals your computer. Backup means copying the sensitive data on your machine and storing it somewhere else, and it's best to have off site backup to your onsite backup, I.E., two different sources to recover data from, in the event of extreme catastrophe.
Recordable DVD/CD media does unfortunately degrade even without exposure to light or usage. The dye just slowly breaks down. Certain dyes are better than others for longevity and these can be found as archival quality. Making periodic copies of your backup volume mitigates this risk of course. Pressed discs on the other hand last pretty much forever I imagine. Your other points are well said
Seaweb,
All this said, I think Time-Machine is a pretty valuable tool because of the way it does backups. But please, for your sake, take the time to make a few DVD backups of the stuff you were REALLY afraid of losing this time around. I'd hate for you to be caught with your pants down again!
