0.057: of blind men and an elephant
For some reason, IBM's brand marketing dude (and Fellow Blogger) Tony Pearson has taken it upon himself to single handedly justify and defend IBM's recently announced acquisition of XIV. (I don't know, maybe its his job, or something.)
In yesterday's salvo he attempts to clarify the alchemy of blob-based replication and recovery. But alas, his logic still doesn't hold up: there's nothing in Nextra that protects against data loss from the inevitable double drive failure, no matter how how hard he tries to mix in irrelevant "facts" to redirect the conversation.
But I'll have to admit he floored me with his "observation" (buried within the follow-up comments) that cosmic rays basically defeat any potential benefits of RAID6! I guess that explains why the DS8000 still doesn't support RAID6 or support drives larger than 500GB, since the DS8000's read memory isn't mirrored and there's no error detection/correction like the SNCDND logic that is utilized in all generations of Symmetrix DMX.
Go figure!
But what shocked me the most was Tony's assertion that SATA drives are cheap enough that the Web 2.0 world can in fact afford not only to mirror them, but also use that mirrored capacity at less than 50% full!
Now, I don't know about you, but in the world I'm living in, nothing could be further from the truth.
doing more with less, every day
Given today's economy and its effect on budgets, the slowing growth in drive capacities and the never-ending growth in on-line storage, IT shops around the world are challenged to do more with less. Every Day.
The customers I meet every week are ALL trying to move away from mirrored data protection and mirrored replication everywhere they can get away with it. They are demanding thin provisioning and thin replicas to drive their overall storage utilization upwards to 60-80%. And when SATA performance is appropriate, they are deploying RAID6 to protect against double drive failures and using the largest SATA drives available.
But like the blind men in this post's title, it seems that there may be some folks over at IBM who haven't quite figured out that there is in fact an elephant in the room (sorry, but after Tony's earlier distasteful elephant reference, I just couldn't resist extending the metaphor in a lighter direction.)
And that elephant is this simple fact secret: the storage market today is about providing robust and reliable storage that meets the intended performance and availability service levels, at the lowest possible total cost of ownership.
Now, I've intentionally written this only here, and not in the comments on Tony's blog, in hopes that Tony's audience back at IBM might not actually see this well-kept secret to success in the storage market. I mean, they'd have no reason to stop by *MY* blog, now, would they?
Alas, it probably doesn't take a wise man to figure out that buying 4 drives to get 1 drives' worth of usable capacity isn't really going to cut it in Web 2.0-land.
let's try some real-world math
Tony's latest article calculates the number of drives required to support a mere 3 TB of usable storage using only 750GB drives. With the liberal application of misdirection and half-truths, Tony attempts to minimize the cost delta between RAID1 and RAID6, making it sound like RAID6 isn't really that much less expensive than fully mirrored storage.
Not surprisingly, the range of drives required isn't all that significant for such a small amount of usable storage.
But remember, Web 2.0 is all about LOTS AND LOTS of Storage. And in fact, the minimum configuration for an XIV Nextra is 40TB (raw) - 20TB (usable).
So, rather than look at what it takes for a mere 3TB of usable storage, let's calculate the number of 1TB SATA drives required to provide 300TB of usable storage (a mere fraction of a typical Web 2.0 deployment, I should think).
Nextra "RAID-X" (Tony's term): 660 drives
i rest my case, your honor
'Nuff said. I think I'll move along to some more interesting topics now...PEACE! 
(Note to readers - if you're new to blogging and/or aren't in the habit of also reading the comments on blog posts, you're missing half the fun. You usually can't see the comments from within most blog readers, so I encourage you to visit the actual blog pages and to peruse the comments attached to the entries that catch your attention. You may find there is a lot of additional perspective that you've been missing!)
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