PCIe Adds Fuel to SSD Performance

Arthur Cole

SSDs provide a dramatic increase in I/O compared to traditional magnetic disks. So it only makes sense that any investment in solid-state storage is accompanied by increased throughput on the interconnect and beyond.

And for many storage professionals, that throughput is coming by way of PCIe.

As Storage Switzerland's George Crump points out in a recent blog, selection of the SSD controller is quite often the key differentiator in overall SSD performance. Not only can PCIe be deployed to address I/O limitations on specific hardware, but it does so without forklift upgrades to wider SAN or NAS infrastructures. Just be careful to establish a robust mirroring strategy so you don't lose the benefit of existing data protection measures.

Adding PCIe to SSDs is leading to some remarkable performance benchmarks. LSI, fresh from announcing a new line of 6 Gb SAS switches, has now come out with the LSISSS6200, a 300 GB PCIe SSD that delivers a sustained sequential/random bandwidth of 1,500/1,200 MBps -- enough for 200,000 sequential or 150,000 random IOPS. The company says it can maintain those figures regardless of the read/write mix, and limits the power draw to only what's available on the PCIe slot. Samples are already on their way to OEMs.

There are even new ways to ensure that PCIe infrastructure remains compatible with existing PCI systems and applications. IDT has a new PCIe-to-PCI bridge that offers advanced buffering and queuing techniques that allow for a smooth transition between the two formats, even though existing PCI systems will only have access to lower bandwidths. The company is targeting the unit at a range of devices, including motherboards, adapter cards, printers, mobile hardware and even DVR cards.

PCIe has the advantage of nearly universal compatibility with enterprise hardware, and there are some who advocate its use as an alternative SAN protocol, although that's probably a stretch for many users.

Nevertheless, with SSDs offering such a dramatic increase in bandwidth at the source, it would be a shame to waste it right out of the gate.

Add Comment      Leave a comment on this blog post
Mar 19, 2010 7:45 AM Eric Slack Eric Slack  says:

Kind of tangent to this blog, but flash controllers  handle a lot of housekeeping tasks, even more than mechanical array controllers. They also do block provisioning, wear leveling (to optimize finite number of writes that flash can sustain) and bit-level error correction. These processes consume CPU cycles, so it matters which CPU in the system is given this burden. The better SSD arrays have dedicated CPU and memory to handle this workload, others put it on the host CPU, which can affect performance. There are a number of details about SSD array controllers in this article   http://bit.ly/8fiaru  that can help differentiate different vendors' products.


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