Rich, On Mon, June 23, 2014 10:37 am, Richard Pieri wrote: > On 6/23/2014 9:41 AM, Stephen Adler wrote: >> drives) and are the favorite for data centers. But there's a factor of 3 >> difference between the storage capacity and size. so the problem is that > > A 24x2.5" storage box takes up three rack units plus one for a server. A > 16x3.5" storage box takes up 6-7 units plus one for a server so for the > same space that the 3.5" box uses I can have 48x2.5" disks. 7 units for > 48TB of raw capacity vs. 7 units for 96TB raw capacity. That's a factor > of 2 at most and only with very expensive 6TB 3.5" disks. The factor > drops to 1.3 with 4TB 3.5" disks and is even on with 3TB 3.5" disks.
I've already showed a counter-example showing this incorrect.. You can get a 24x3.5" 4U case. So for an extra 1U I can get the same number of drives, which gives me 2x-3x on space (largest 2.5" drive I can see right now is 2GB, vs 4-6GB 3.5" drives). Of course the 2GB 2.5" drive is only 5400RPM, and as of right now costs $118 from NewEgg, versus a 7200RPM 4GB drive for $184. So for an extra 1U and 1.5x the cost I get 2x the storage and more speed (because it's still the same number of drives, but 7200 v 5400 RPM). The running cost, of course, is a little more heat and power. > There's the performance gain. Three 2.5" 7200 RPM disks together are > substantially faster than a single 3.5" 15K RPM disk for less power and > less heat which saves money on cooling costs and is good for drive > longevity. That presumes you do run more 2.5" drives than 3.5" drives. And doing so drives up the cost. To get the same amount of space I need 2-3x the number of 2.5" drives. At that point is it really still a power/heat savings? Are 2.5" drives really using less than 33-50% of the power of a 3.5" drive? > > Dell still offers most of their *Vault line with 3.5" options. There are > also plenty of bare chassis out there to build your own. -derek -- Derek Atkins 617-623-3745 de...@ihtfp.com www.ihtfp.com Computer and Internet Security Consultant _______________________________________________ Discuss mailing list Discuss@blu.org http://lists.blu.org/mailman/listinfo/discuss