I have a storage server (RHEL 5.2) and (2) 2U DAS chassis containing 24 drives each (48 drives total). The server has dual LSI 9280-8e SAS RAID controllers. My goal for this setup was to aggregate performance across both RAID controllers, but I'm having trouble doing so.
To troubleshoot I first connected each controller to (1) 2U DAS so each was able to see 24 drives. I setup a RAID0x24 for each. After benchmarks using Iozone, I was seeing sustain writes of 1650 MB/s for each controller. LSI advertises 1800 MB/s writes with their LSISAS2108 chip, so I'm pretty much right at the margin.
In order to combine the throughput across the controllers (1650 Mb/s * 2 = 3300 MB/s max) I created a RAID0 array in mdadm. When I do this, I'm still seeing a max rate of 1650 MB/s, which doesn't make sense. I'm wondering if I'm missing something. I've tried various strip sizes for the hardware and software RAID with no success.
To troubleshoot I first connected each controller to (1) 2U DAS so each was able to see 24 drives. I setup a RAID0x24 for each. After benchmarks using Iozone, I was seeing sustain writes of 1650 MB/s for each controller. LSI advertises 1800 MB/s writes with their LSISAS2108 chip, so I'm pretty much right at the margin.
In order to combine the throughput across the controllers (1650 Mb/s * 2 = 3300 MB/s max) I created a RAID0 array in mdadm. When I do this, I'm still seeing a max rate of 1650 MB/s, which doesn't make sense. I'm wondering if I'm missing something. I've tried various strip sizes for the hardware and software RAID with no success.