Inside System Storage -- by Tony Pearson

Tony Pearson Tony Pearson is a Master Inventor and Senior IT Specialist for the IBM System Storage product line at the IBM Executive Briefing Center in Tucson Arizona, and featured contributor to IBM's developerWorks. In 2011, Tony celebrated his 25th year anniversary with IBM Storage on the same day as the IBM's Centennial. He is author of the Inside System Storage series of books. This blog is for the open exchange of ideas relating to storage and storage networking hardware, software and services. You can also follow him on Twitter @az990tony.
(Short URL for this blog: ibm.co/Pearson )
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1 localhost commented Trackback

LOL!<div>&nbsp;</div> Yes Tony, you are right. <div>&nbsp;</div> The maximum usable capacity of a Symmetrix is in fact directly linked to the amount of memory in the system and the RAID protection type used by the drives. With the current maximum of 512GB (256B usable) Global Memory, the max usable capacity of a DMX-4 falls in the 600-650TB range for RAID 5 &amp; RAID 6 (it's a little higher for fully mirrored configurations, IIRC).<div>&nbsp;</div> But this isn't something that EMC has tried to keep secret. <div>&nbsp;</div> There is no conspiracy to hide the facts. In fact, had you looked, you would have noticed the same thing in prior versions of the DATA sheet with RAID 5 configurations of the 500TB drive.<div>&nbsp;</div> What the data sheet SHOULD have said is that 1TB drives allow you to reach maximum usable capacity using 1/2 as many drives as before.<div>&nbsp;</div> "These are not the 'Droids you are looking for...now Move Along"<div>&nbsp;</div> But I fail to see why you'd even bring this up - you are merely highlighting the limitations of your own poster child.<div>&nbsp;</div> For those playing the home game, the DS8000 Turbo only supports 1024 drives maximum, and the largest drive it supports is the 500GB LC-FC (FATA). That means that the DMX-4 can support MORE THAN twice the usable capacity of your flagship storage array.<div>&nbsp;</div> And the DMX-4 can support the SAME capacity as a DS8000 Turbo using only half as many drives - with the added benefit of requiring less power and floor space.<div>&nbsp;</div> Thanks for the opportunity to clear that up for your readers...

2 localhost commented Trackback

Oh - almost forgot: <div>&nbsp;</div> * the DS8000 Turdo doesn't support RAID6<div>&nbsp;</div> * the DS8000 Turbo doesn't support SATA drives<div>&nbsp;</div> * the 500GB FATA drive that the DS8000 Turbo DOES support isn't manufactured any more, and AFAIK there is no larger FATA drive available from anyone<div>&nbsp;</div> Like I said, Tony, I'm not exactly sure why you bring these things up...

3 localhost commented Permalink

... "your Jedi mind tricks won't work on me" ...<div>&nbsp;</div> Size isn't everything... and it all comes back to if you really want that much low IOs SATA in a big expensive box. OK, so they can do reasonable MB/s for streaming, but buses/ports are going to be the limiting factor there.

4 localhost commented Permalink

Neither of us are saying it shouldn't be done, just that there are alternative that may work out cheaper and more effective in a lot of accounts - just don't think its a big a thing as you make out. <div>&nbsp;</div> But then we that maybe because we have a virtualization device that works and delivers on its promises, are happy to let customers choose to reduce vendor lock-in, and have more more on our supermarket shelves so aren't as protective as a speciality shop which relies on its monoloth to make its money (i.e. DMX licenses). Once you take the value out the monolith, its just a monolith - I guess thats why Invista is so low key.

5 localhost commented Trackback

Like I said - it was IBM who brought up the issue of 1TB SATA in the DMX, and tried to make folly out of the max capacity supported. I merely clarified your abject misunderstanding four our readers, and in no way said that the DMX-way is the only way to support multiple tiers.<div>&nbsp;</div> But now that you mention it, there obviously remains some significant value in "monolith," since that is precisely what both the DS8000 Turbo and the XIV NEXTRA are. <div>&nbsp;</div> It is obvious to everyone that you're only dissing monolithic because you can't deliver a DS8000 Turbo Monolith big enough (or functional enough) to compete with either USP-V or DMX. <div>&nbsp;</div> And heck, you guys practically INVENTED proprietary, lock-in and specialized. But it's not working out in storage like it did with the monolithic mainframe, where you happily hold an effective monopoly at the high end. <div>&nbsp;</div> Bummer.<div>&nbsp;</div> And while the NEXTRA monolith may indeed be a monolith made up of industry standard parts, it is no less proprietary, lock-in or specialized. Although we've yet to see IBM's pricing strategy for Nextra, XIV's was built entirely on expensive software licenses with recurring maintenance fees. Gotta feed the engine somehow.<div>&nbsp;</div> The undeniable fact is that there is clearly room in this world for several different models. <div>&nbsp;</div> But there is undoubtedly a lot more that the three of us could be adding to the community than continually trying to score petty body shots on each other. I mean, come on now, a WHOLE SENSATIONALIST BLOG POST about the fact you don't understand how a DMX is configured? <div>&nbsp;</div> Better to have kept one's mouth closed...

6 localhost commented Trackback

BarryB,I don't understand the more than twice comment. Maximum usable for DS8000 is 448TB with 500GB drives, compared to 586TB that DMX-4 offers. That's only 30 percent more. Architecturally, DS8000 can address 8PB of data, and I agree I was not aware that DMX-4 was architecturally limited.

7 localhost commented Trackback

I acknowledge my mistake - my apologies. I wrote the "more than twice" and hit send before I remembered that the DS8000 doesn't support RAID-6. The current DMX-4 does indeed support only 30% more usable capacity than the current DS8000, and it does so using 1/2 as many disk drives.<div>&nbsp;</div> Architecturally, the DMX can also support multiple petabytes of data, it is the current hardware packaging that imposes the limit, as is also the case with the DS8000.<div>&nbsp;</div> But it really doesn't matter what the architecture COULD support now, does it? We're talking about what customers can buy today here, aren't we? <div>&nbsp;</div> And there's no denying that the DS8000 implementation supports less capacity today than the today's DMX, and that the DS8000 requires twice as many drives to reach the same amount of usable capacity than does the DMX. As an added benefit, that makes the DMX inarguably the watts/GB "greener" solution.

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