I have 6 identical hard drives and two on-motherboard SATA controllers. When I tested each drive individually, they were all the same speed. When I tested all the drives simultaneously, the drives on one controller were half the speed of the drives on the other.
It turns out that on the first controller you get four ports and when you attach drives to those ports they all get set as master (ie. there are 4 channels). On the second controller there are also four ports, but you actually get master/slave master/slave (ie. there are only 2 channels). With that setup, I only get half the bandwidth per drive when using all the drives. Consider a file server with one user. All 6 drives are combined into one RAID-Z2 vdev. Under what circumstances will the master/slave setup really hinder performance? Would a scrub or resilver use a master and a slave drive simultaneously? Are there single-user usage scenarios that might use a master and slave simultaneously? I could buy a new controller to avoid this conflict, but that's more time and money. If real-world use would not use these drives simultaneously, I will get satisfactory performance just how it is. What do you think? -- This message posted from opensolaris.org _______________________________________________ opensolaris-help mailing list opensolaris-help@opensolaris.org
