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OCZ's HSDL: A New Storage Link For Super-Fast SSDs

OCZ's HSDL Interface

OCZ's IBIS is an interesting piece of hardware, but I'd argue that it isn't the focus here today. Rather it's the company's High-Speed Data Link in the hot seat, theoretically able to move up to 2 GB/s over a very PCI Express-like bus.

Unfortunately (or fortunately, depending on how you look at it), even a 3.5" drive with four SandForce SF-1200 controllers and 240 GB of Intel NAND flash cannot come close to saturating the interface. Without question, we'll have to wait for the mysterious next-generation IBIS drive OCZ's CEO Ryan Petersen mentioned.

With that said, the stage is set for an interesting evolution. A single HSDL channel and a first-generation drive outpaces what one SAS connection can do, throughput-wise. And OCZ is talking about multiplexing lanes to generate even more performance. You can't do that with SAS. SAS is great for taking four ports, hooking them up to a midplane, and attaching 20 drives. But if performance is your one and only care in the world, you can't take those same four SAS links and route them into a single drive. Even if you could, we haven't seen a single SAS-based device able to push the interface's maximum 600 MB/s--much less the numbers OCZ is throwing around.

It might seem silly, then, to already be talking about a two-channel PCIe x8 card able to move 4 GB/s. Armed with four ports, though, it's almost mind-boggling to think about what a quartet of IBIS drives could do for highly transactional workloads in a single server. I'm almost positive that it'd be impossible for me to justify spending more than a grand on 360 GB of capacity, as an enthusiast. But I know for a fact that there are plenty of business applications for this--environments where the capacity and cost aren't issues, but performance is.


Alright, so we know that HSDL in its current form theoretically has gobs of headroom to spare. Where does that leave IBIS, the first drive family designed to take advantage of the HSDL interface? The way it stands right now, most of the IBIS drives are, simply, expensive. This isn't OCZ's play on performance for the price--that remains the RevoDrive, according to the company. Here, you're paying a premium for product that can deliver more than 100,000 IOPS and streaming read/write performance in excess of what a SAS port serves up. OCZ says enthusiasts are in its reticle here, but I don't really see any practical reason for power users to go this route, unless you have an application you know is outright I/O-limited. The more receptive markets are going to be Web servers, file servers, databases, and email.

Shoot, if OCZ could partner up with a storage software vendor and create a caching package that'd operate similar to Adaptec's MaxIQ or Intel's SSD Cache premium feature key, it'd have a massively powerful solution for speeding up application performance--like a miniature GridIron TurboCharger.

Bearing in mind that the IBIS seems tailor-fit for the enterprise space, my main reservation right now would probably be a lack of features you normally find in more business-class storage solutions, such as battery backup to prevent against loss in the event of power failure. OCZ's SF-1500-driven Vertex 2 Pro employs a capacitor that stands in as a temporary backup, allowing the SSD to finish outstanding operations before losing power. You don't get that concession on an SF-1200-based implementation like IBIS. That'll be something IT decision makers, who are a notoriously conservative bunch, have to consider before jumping on this technology. We're also missing TRIM support here, and it remains to be seen whether this affects performance over the long term.

Regardless, IBIS is OCZ's first generation of what will hopefully turn into a wider range of HSDL-based SSDs. It's incredibly fast today, and the company is talking about forthcoming versions able to tax its interface in an even more significant way. PCIe-based SSDs are cool, but I'm looking forward to seeing HSDL make ultra high-performance drives more flexible. And that's really what this technology is all about. Four super-fast drives plugged into an HSDL PCI Express card is much better in a server than four drives plugging up their own slots.

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