I'm somewhat surprised ADI even knows the term RAID except, perhaps, when it applies to bug killers ;-o
What? That's an absurd statement!
Do they really know what they're talking about?
Hummm...at Pivot3 it was RAID5 minimum or RAID6 (or RAID5e and RAID6e) and on every project every servers are RAID5 or RAID6 (if there's a lot of storage like 4U chasis).
If you go RAID1, it's OK for small installation but for big one, no way. it makes no sense...
RAID 1 actually does make a lot of sense depending on which variables are most important to the customer and to you. Cost is only one of the variables.
Before jumping in, here's one of many many articles on the issue: http://www.thedatacave.com/raid-5-is-dead
Here's just three considerations.
1) Hard drives are inexpensive and delivering say 64TB instead of 32TB is not that expensive.
2) RAID 6 will also suffer from URE's that make the RAID non-recoverable at some point. It's just a matter of time and total storage size before it affects you.
3) RAID 1 is much faster and no major rebuild times compared to 5/6 and can be dealt with by the user much easier. This frees up your time which has a value as well.
There's more, but true redundancy in many cases can have a lower TCO than fancy, prone-to-failure parity RAID solutions.
Of course having your customer (and his IT staff) laugh in your face when you suggest RAID 1 may have it's own pitfalls.
If you'll read the initial post, it says "Studies have indicated that the reconstruction of data using RAID 5 configurations can be a hit or miss proposition."
I was amused with the "hit or miss proposition" statement. We all know, regardless of the configuration, that there is enough parity information in the array to reconstruct the data.
Yes, I agree that with RAID1, there is effectively no down time when one drive goes down. I use RAID1 for my boot drives just for this reason. For data storage I used RAID5 for better perfomance and increased reliability. Statistically, the chances of one drive failing in RAID1 is 50%; the chances of one drive failing in RAID5 with 3 drives is 33%.
A "sure method of automatic backup"? RAID isn't a backup, it's redundancy. RAID1 is fine if you only have two disks but if you have more you want RAID10. I had a couple customers that used RAID10 for all their apllications because of the rebuild times of RAID5. This is why I never used ADI for any engineering at my last job and anytime I asked them for some obscure item I triple checked it to make sure it was the correct item. What a joke.