Jon Toigo  |
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Jon William Toigo is directeur en eigenaar van Toigo Partners
en voorzitter van The Data management Institute LLC. |
09 november 2011 - Metrics that matter
Steve Sicola, who serves as CTO for Xio, told me earlier this month that his company has decided to stop producing high-capacity versions of their storage blade array, the Intelligent Storage Element (ISE). Instead, they will focus more narrowly on delivering a very-high-speed lower-capacity building block that uses SAS and flash SSD drives. The current ISE is one of the fastest rigs on the planet, with a Storage Performance Council metric of 200,000 IOPS.
That number was recently eclipsed by test results from HP’s latest 3PAR system, which boasts twice the IOPS measure. It can reach those figures, I am told, by throwing a lot of so-called short-stroking disks at the challenge. By contrast, Xio’s ISE gets its speed from a kind of sub-LUN tiering that uses flash SSD’s to optimize the performance of SAS disks. This means fewer drives and less power consumption than the 3PAR kit.
Power pig
I mention this because of something Sicola told me. He said that his customers are seeking the highest number of IOPS per watt. That is the metric that matters, the CTO confided to me. If you look at it that way, Xio still knocks the socks off its HP competitor, he says. But this is true only if consumers will see IOPS per watt as the metric that matters most.
Sicola is correct. In north-east America and in northern and southern California, where data centres tend to congregate, my clients are experiencing difficulty in getting utility providers to drop another power line into their data centres. That’s bad news, since, firstly, data continues to proliferate, resulting in ongoing demands for more storage capacity, and, secondly, more capacity tends to demand more energy.
A couple of years back, Dell admitted that storage was passing servers as the biggest power pig in the data centre. Additionally, Gartner is saying that server hypervisor adoption is expected to increase the demand for storage capacity by 600 per cent over the next couple of years. This growth is caused mainly by the replication of data to safeguard it against the giant Jenga game that is VMware and to provide minimally acceptable I/O performance to guest apps.
NAS on steroids
Okay. So IOPS per watt is, if not the most important metric, at least one of the most important metrics that matter. It matters more than capacity per dollar, euro or shekel. It matters more than most other traditional measures, for that matter. Sicola’s observation is especially on point if you consider another storage development: the rise of tape NAS. Within the next month or so, you will hear about innovative products that combine a file system with a tape library. A stand of disk will provide a cache function to help the platform perform. It’s like a multipetabyte NAS for the price of a small disk array, which could be a very interesting idea to compliment Xio’s fast-capture storage.
That’s right. That crazy tape library with its file system in front will provide the storage capacity to hold nearly 70 per cent of all data, because that information is hardly, if ever, accessed. We are talking about a price of below a dollar, euro or shekel per gigabyte on a platform that could store tens and soon hundreds of petabytes of data on a single raised floor tile. In terms of power consumption, it will be like a couple of desk lamps. Retrieval of files from the tape NAS will take longer than from rotational disk, of course. But it won’t be much slower than downloading a PDF file, a music file or a video from a website, which we do every day. Think of it as a NAS on steroids.
There is merit in the ideas of Xio and tape NAS. Both can be justified by simply using a compelling per-watt metric. For Xio we measure in terms of speed per watt, for tape NAS in terms of capacity per watt. This might just be the start of some intelligent storage solutioneering, driven by the most compelling and pragmatic concerns that planners face today: energy availability and cost.
I intend to cover this evolving storage-building model closely. Looking at tape, we see the advent of LTO cartridges with a 32 TB storage capacity. Looking at Xio’s smart use of flash SSD, we see it’s not being used as a write target, but as a temporary repository for hot data to increase the IOPS of a disk subsystem. I suspect that we are on the doorstep of an interesting storage architecture. Watch this space for more.