Well, I've tried setting up Unraid in VMWare Fusion 4.1 but unfortunately it cannot find Networking drivers and thus only has the loopback 127.0.0.1 IP. Will figure that out later.
Can you explain to me how that HP SAS Expander works? I've got no experience with SAS beyond the connector built into my current HP MicroServer. Can I connect multiple SATA into a SAS Channel or similar? *n00b storage question*.
Sure. Basically the HP SAS Expander features 8x8087 SAS and 1x8088 SAS ports. Each port is basically four singular SAS connectors bonded together.
You can use an 8087 to SATA cable to take one of the 8087 ports and 'fan it out' to connect four hard disks. So with that one expander you can get a potential of 32 Disks connected by using 8x8087 to SATA cables. These cables each cost about £8-£10 retail and you can fit four SATA or SAS hard disks per cable.
Now the 8088 SAS port on the card is just the same as an 8087 but its the external version. So the connector is a bit more beefy and it's on the back of the cards bracket which sticks outside the case. This is the connector I've chosen to use with my RAID card so I can use all 8x8087 ports for 32 Disks. On my RAID card it has 2x8087 connectors so I'm using a 8087 to 8088 cable to take one of those connectors on my RAID card outside of the case through a water cooling grommet in my case and in to the back of the expander.
The HP SAS Expander supports 6Gb/ps when used with SAS disks but it only supports 3Gb/ps when used with SATA disks. This isn't a hardware limitation just something HP has done with the firmware to make the card more attractive to enterprise customers. It still works fine with 6Gb/ps SATA disks but it negotiates them at the slower 3Gb/ps speed.
Most SAS RAID cards which support SAS2008 spec (you'll find this listed on their websites or manual usually) should work with the HP SAS Expander but to be honest it's not always that cut and dry. The best RAID cards compatibility wise feature an Intel processor. Cards such as the Highpoint 4330 4320 4321, LSI 9620 series (4i, 8i, 16i) all work fine with the Expander.
It's cost effective but to a certain point. The HP SAS Expander retails for around £330 in the UK and then you still need to shell out around £100 on cables and about £200 minimum on a compatible RAID card. The main benefit is a 32 port RAID card with RAID6 support is around £1200 so it does cost less than one of those and you always have the option of using the expander in a future system. In my case as I'm using an LSI 9620-8i which features two 8087 connectors I could buy another expander and double my storage potential to 64 disks.
Something else to note is that the expander is not seen by the operating system. Although it connects through PCIe it only does so to receive power and doesn't communicate its presence to the computer at all. Thus it is possible to power it separately from the motherboard you're using it in and it still works fine. It also means it "just works" no configuration needed beyond plugging in the cables and powering the computer on.