Data Rate Optimization on the NI 8261

Updated Mar 15, 2018

Reported In

Hardware

  • HDD-8261

Issue Details

  • I want to know when I get the SSD version of the NI 8261, that it can transfer 2 GB/s from Windows memory to RAID. Is there anything we would need to do to achieve this?
  • I recently purchased the NI 8261 and I would like to configure it for optimal performance.

Solution

NI 8261 HDD

  • The NI 8261 HDD has been optimized to provide write speeds of up to 250 MB/s in RAID 0 across approximately 80% of the disk capacity.
  • ​For the HDD-8260 and 8261 3-slot wide in-chassis RAID modules, you must use software RAID (such as Windows software RAID) because there is no hardware RAID controller on the device.
  • The NI 8261 HDD performs best in a PXIe-1085 with fans set to Auto. With fans operating on High, performance is degraded due to increased vibrations. The below graphs depict performance versus fan speed. Whenever possible, install the NI 8261 HDD in slots 2-6. 

Figure 1. NI 8261 HDD write speeds versus the amount of data stored in the HDD


Figure 2. NI 8261 read speeds versus the amount of data stored in the HDD

NI 8261 SSD

  • The NI 8261 SSD has been optimized to provide write speeds of up to 2 GB/s.
  • The NI 8261 SSD performs best when placed close to the controller slot and used in a PXIe-1085 or equivalent chassis.
  • While utilizing the NI 8261 SSD, avoid adding or removing any I/O cables from the controller to avoid buffer overflows and maintain full throughput. If the NI 8261 SSD is used in a headless system, speeds may be reduced to ~1.5 GB/s.
  • For continuous streaming at 2 GB/s, a 2 GB host DMA buffer is needed to protect against the SSD performance inconsistencies. DMA buffers this large require 64-bit LabVIEW.

Additional Information

For general streaming considerations, see the Optimizing Streaming Performance white paper.

With software RAID, there is no RAID controller onboard memory to serve as a buffer/cache, large host buffers are necessary to hit target data throughput rates.

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