Date: Tue, 06 Jul 2010 19:35:40 -0400 From: Stephen Sanders <ssanders@softhammer.net> To: freebsd-performance@freebsd.org Subject: More Controllers != Higher Through Put Message-ID: <4C33BDCC.1020004@softhammer.net>
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I'm wondering if anyone has heard of this. I've a system with a 3ware 9650 servicing 4 7200RPM Segate 1TB drives and the motherboard servicing 2 7200 RPM Segate 1TB drives. The 4 disk array is RAID 6 while the 2 disk array is RAID 1. The drives should deliver about 100MB/s. 1. The most the 4 disk array is developing is 250MB/s write performance while the 2 disk array is coming in at 90MB/s write performance. The 4 disk array seems slow. 2. Attempting to write to both arrays simultaneously causes the rate on the 4 disk array to drop to 150MB/s and the 2 disk array drops to 60MB/s I'd expect the 4 disk array should look more like 300+MB/s while the 2 disk array is about right. I don't get why there should be a 'coupling' between the rates on separate controllers. The system is running FreeBSD 8.0, has 16GB of RAM in the system, and the test program is using O_DIRECT for writes in order to avoid the page daemon. Thanks
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