While working on a client configuration for a VMAX 20k – and this may apply to the 40k as well, as I haven’t checked – I encountered something odd: The 20k supports up to 2400 3TB drives, according to the EMC 20k spec sheet. That should be a raw capacity of 7.2PB
However, the same spec sheet appears to say that the maximum usable storage capacity – after taking care of formatting overhead, system needs, etc. is ≈2PB. Here’s the table from the spec sheet:
Coming at it from other directions, it seems that since the 20k supports four 60 drive enclosures per rack, and supports 10 drive racks – with a lot of daisy-chaining – you can indeed connect 2400 3.5″ SAS drives. So where us the discrepancy?
Try as I might I can’t reconcile it. Simple spec sheet error? I can’t read? Are large capacity drives short stroked? Is the NSA using the rest? What’s up?
I know there’s a lot of EMC expertise out there, so please, enlighten me!
The StorageMojo take
I’ve been looking at a number of systems this week. As far as large vendor product info goes, EMC and NetApp are the least forthcoming, HP the most, and HDS in the middle.
Normally withholding information from customers is meant to ensure a call to their friendly Sales Engineer, but perhaps it is to imbue passivity into customers. “Boy, I can’t figure this out. Why even try?”
Perhaps more on this topic later. I’ve also thought of twist on the Price Lists that may justify un-deprecating them. Your thoughts?
Courteous comments welcome, of course. Update: If I were in competitor product marketing, especially for flash products, I’d be updating my “flash is competitive with disk” slides tonight. End update.