Thanks for that. The only thing out of the ordinary is that write cache is disabled because you have no Standby Power Supplies (SPS). The SPS are a mini UPS that keeps the array running for about 2 minutes after a power failure so that the array can flush the contents of write cache out to the vault area on the first 5 disks. No SPS = no write cache = pretty ordinary write performance.
I'd be very surprised if you purcahsed a CX300 without SPSs - it is more likely that they aren't connected correctly. Your CX300 contains a 3U cabinet chock full'o disks. Beneath that (typically) is a 1U tray with 1 or 2 SPS in it. From the rear of the cabinet, you should see the main power cables going from the supply to the SPS, then a shorter mains cable going from the SPS to the CX300. There is also a small signal cable that tells the array what state the SPS is in.
Can you check the cables please and post what you find? A photograph would be helpful too, if you can.
