Hands on: Raid controllers

Results
With all four disks connected to the TX4310 and configured as Raid 0, the array measured 1.2TB and delivered average read and write speeds of 104Mbytes/sec and 72.8Mbytes/sec, respectively, with a 106Mbytes/sec burst rate. Switching to Raid 5 on the TX4310 delivered a 900GB array, with average read and write speeds of 92.1Mbytes/sec and 12.1Mbytes/sec, respectively, and a burst rate of 102Mbytes/sec. The TX4310 arrays used the controller’s default 16KB block size.

With all four disks connected to the EX8350 and configured as Raid 0, the 1.2TB array delivered average read and write speeds of 138Mbytes/sec and 74Mbytes/sec, respectively, with a 257.1Mbytes/sec burst rate. Switching to Raid 5, the 900GB array delivered average read and write speeds of 125.3Mbytes/sec and 69.1Mbytes/sec, respectively, with a 241.6Mbytes/sec burst rate.

The EX8350 results were using the smallest 32KB block size, although we tested at the 64KB and 128KB settings. The overall Raid 0 performance decreased slightly with larger block sizes, and while the Raid 5 read performance also fell with larger block sizes, its write speed increased to as much as 80.2Mbytes/sec.

Superior performance
The EX8350 clearly delivers superior performance. By exploiting the faster PCI Express interface, its read and burst speeds are greatly increased, but the most impressive figure is the Raid 5 write performance. On the software-based TX4310, the Raid 5 array delivered a paltry 12.1Mbytes/sec. In stark contrast, the hardware-based EX8350 boasted Raid 5 write speeds of at least 69.1Mbytes/sec, which matched its Raid 0 write performance.

Hardware acceleration removes the major downside to Raid 5 and allows arrays to be used for high-performance applications such as recording video streams. If you want uncompromised Raid performance, go for a hardware card on a PCI Express bus.