Storage grows greener

[InfoClipz: Green tech | Video: Hitachi CTO talks green storage ]

There are a couple of reasons for that. First, data simply continues to pile up. Second, as that data piles up, datacenter operators have an unfortunate habit of throwing more storage at the problem, rather than making better use of what they’ve got. That approach ends up costing you in several significant ways. You’re laying down cash for new or leased storage arrays. You’re paying monthly bills to power and cool those arrays. And you’re sacrificing precious datacenter space for potentially superfluous hardware.

Surprise, surprise, storage vendors out there are keenly aware of the problem and are devising storage technology and products that could play a critical role in your green datacenter blueprints. Among those vendors is Hitachi Data Systems (HDS). The company’s CTO, Hu Yoshida, recently sat down with me to talk about the subject. (You can watch the video here.)

Data diet

One resource-saving storage technology being pushed by HDS and other vendors, including HP, is thin provisioning. The premise behind the technology is pretty straightforward: It lets IT admins view all of their storage hardware as a great big pool and divvy up slices as needed, rather than allocating separate arrays for different business units that might not be taking full advantage of the pricey hardware you’ve set aside for them.

The result, if all goes well: You can purchase just enough storage machinery to meet your organization’s collective needs, which means you’re paying less money for arrays that are sitting there running at 20 percent utilization while you pay for 100 percent of their drives to spin. That doesn’t make a lot of sense economically or environmentally. (There’s also the benefit of easier management, but my sites are set on green.)

For thin provisioning to be effective, careful planning is, of course, critical, a point that’s certainly not lost on InfoWorld storage guru Mario Apicella. If various departments estimate they’ll need 8TB of storage but, lo, it turns out they collectively needed 10TB (oops!), you’re left in an unenviable situation of playing storage catch-up.

But then, that’s the challenge of running a green datacenter in general: You have to be sure you forecast and budget intelligently such that you always have just enough servers, storage arrays, and other hardware up and running at one time. That’s fodder for another blog post, perhaps. On to additional green storage approaches.

Put the brakes on drives

In my interview with Yoshida, he talked about the new power-management capabilities, called Power Savings Storage Service (or secretively, PSSS), which the company recently introduced in its mid-range Adaptable Modular Storage (AMS) and Workgroup Modular Storage (WMS) systems. Once again, the premise is pretty straightforward: You have an array with various drives, but this feature gives you the ability to put drives to sleep when they’re not being used. That means, of course, that you’re not paying to power something pointlessly.

This technology might sound familiar to you if you’ve read about MAID (massive arrays of idle disk) technology. MAID storage systems also have drives which can be woken up individually and put to sleep. But there are key differences, which Yoshida has taken pains to clarify in his own blog. He goes so far as to say that PSSS is the opposite of MAID: PSSS works by putting active drives to sleep whereas MAID works by waking up sleeping drives.

The approach differs because the applications are different. The AMD and WMS arrays are RAID systems storing production data. “These HDS RAID arrays are production arrays that have no restrictions on writing or reading and can have high-performance [Fibre Channel] RAID groups and/or lower cost SATA RAID groups,” Yoshida writes. “Instead of keeping all the disks idle until they are accessed, this feature enables a user or scripted application to power down a RAID group when it is not being accessed and power it back up when it needs to be accessed.”

MAID, on the other hand, is geared for SATA drives storing write once, read occasionally data; that is, data stored on large-capacity drives that you access infrequently and can afford to wait for.

Yoshida concedes that MAID does technically consume less energy, which isn’t surprising, considering that California utility PG&E has offered incentives for companies to enlist MAID. Byte and Switch reports that “users have already shaved around 75 percent off their energy bills through MAID, thanks to the fact that disks are typically idle. HDS, on the other hand, is touting potential savings of around 20 percent as a result of its reliance on active disks.”

Of course, there’s no reason you can’t employ MAID and HDS’s arrays at the same time. In our interview, Yoshida noted that they can certainly be complementary. Yes, MAID might use fewer kilowatts, but when you’re building a green datacenter, you can’t simply focus on the product that uses the least energy — another point that Yoshida emphasized. Rather, the idea is to assemble the equipment that meets your present and future needs while wasting the fewest resources possible. Again, that takes plenty of planning, but the payoff can nonetheless be significant.