At work I have an old Dell SC1435 server that I've been using as a Proxmox server.  It has always been a dog when it comes to IO performance.  It has a basic dell raid card, but it has no battery backed ram, so the write speed has always been slow, and it seems like the raid card is using sata I (1.5Gb/s ) links since I can never get over 140MB/s from it.  The card is a LSI Logic / Symbios Logic SAS1068 PCI-X Fusion-MPT SAS -SAS5/iR . 
 
The Dell specs say that it has a sata II controler, but they lie.  It has a broadcom HT-1000 IO controller, which also says it provides 4 SATA II ports, but the specs then state that each port is SATA I, so more lies.  So even when I switched to using the onboard SATA I still can only get 140MB/s from a Intel 730 240GB SSD.
 
So I'm going to try a cheap Syba  SATA III card with a 2x PCIe interface, which should let me get close to maxing out 2 Intel 730 240GB SSD's and give some more life to this old machine.  I'm planning on running linux software raid 1, which in certain situations, multiple reads, allows both disks to be used at the same time.  The write speed of the 730 240GB is only 250Mbit/s, so that won't be hard to max out for both drives in this situation also.
 
Josh Stompro