Cost Per TB

Greetings and welcome back to my blog !!  I think i’m starting to get the hang of this !!  Hopefully you will agree !!

In my blog post titled Performance Starved Applications we specifically zeroed in on those storage array vendors whose best practice is to keep their systems below a certain utilization rate for performance reasons. If you recall, I mentioned that in our Emprise product line, using ISE technology, we do not have these issues.  Not only can you use more than the industry standard 75%, WE ENCOURAGE YOU TO RUN IT AT 95%% FULL!!!!  Heresy I know!!  We are such rebels over here!!

Let me give you some more food for thought on why this should be important to you.  Why should you pay for the 25% capacity you don’t use?  This is only a big deal if you don’t have an unlimited budget :).  Many times a prospective storage buyer just zero’s in on the upfront costs which in most cases is really misleading.  I like to look at this in a sort of “Cost vs. Value” thing if that makes any sense.   If you’ve ever considered “Cost Per raw TB” as one of the metrics towards the purchase of an array, you want to read further!!

Full disclosure here; I “borrowed” ALL of the following information from Roger Kelley, Principal Storage Architect for the Xiotech Western Region.  He put the “Rock” in Rock Star and I’m not above “borrowing” his ideas!!  His are ALWAYS better than mine anyway!!!  Don’t they say stealing is the perfect form of flattery?  I’m pretty sure that’s how it goes 🙂

Cost vs. Value

If I offered to sell you a 100TB SAN for $1000 how many systems would you buy?  Would you consider $10.00 per TB to be a good deal?  I’m mean COME ON it’s freaking $10.00 per TB!!  What if you bought it, got it to your datacenter, installed it, powered it on, opened up your server and found out that all but 1GB of capacity was used for other things?  The upfront cost maybe AWESOME but it’s far from a good value right?  If you can only use 1GB of that 100TB solution you are actually paying $1,000.00 per GB or $1,024,000 per TB!!!  OUCH.

We at Xiotech have referred to this as the industry’s “Dirty little secret”.  This secret is all about highlighting the upfront cost based on “raw” capacity which makes their configs look great.  As you can see from the example above, that doesn’t make this a good value.  Upfront cost per raw TB, in my opinion is not a good thing to focus on.  In my PSA blog we talked about the common industry “best practice” usable being about 75% right? Probably one of the best discussion on this dirty secret happened over at Chuck Hollis Blog back in 2008.  He basically had a “Slap Fight” comparing his EMC (CX4=70%) with NetApp (FAS=60%) and HP (EVA=70%) on their various utilization rates. (STOP don’t leave yet – finish my blog, comment at the bottom how great this was and then go to his and reference my blog while you leave him a comment).  The comments are the place you want to spend your time in.  It’s just a classic slap fight.  You should bookmark it for future reference.  If I can take a moment for some gratuitousness I just want to do a little SHOUT OUT to Chuck Hollis.  I want to be you and Rob Peglar when I grow up!!

Again, I’m not trying to pick on anyone in particular.  This could be any one of the following solutions (or all of them): Clariion, EVA, FAS, Compellent Storage Center, Xiotech Magnitude 3D, etc.  These solutions are typical and represent a vast number of installed arrays.  At the end of that day it’s important to not get wrapped around the axel on “cost per RAW capacity” but to zero in on “cost per useable capacity”.    Unless you just like paying more money then you should!!

Thanks,

@StorageTexan