Need CPU help: VT-D or Raw Device Mapping

[wbburden]

This is all very new to me. I currently have a Supermicro MBD-X9SCM-F-O motherboard with 8GB RAM and need help with my CPU choice. My plan is to install ESX 5 and run Unraid and a few other guest VMs. I doubt I'll ever need more drives than what the motherboard supports so I don't have a SATA expansion card.

 

Do I need a Xeon chip that supports VT-D to run Unraid as a VM? Can I do the same thing with a non VT-D chip by using RDM? What's the difference? The cost difference between what I'm looking at is substantial.

 

Intel Xeon E3-1230 Sandy Bridge 3.2GHz for $239

Intel Pentium G620 Sandy Bridge 2.6GHz for $70

 

Should I consider something else from either the VT-D or RDM camp? Thanks for any help you can pass on.

[prostuff1]

go vt-d

 

What case are you using and how many drives are you planning on using in unRAID.

[wbburden]

I got the Antec 902 on sale on NE for $69. That seemed like a good move since I can expand into it if needed. Initially, I've got 3 2TB drives and will probably pick up a 500GB drive for the ESX VMs. I don't really see myself using more than 4-6TB but who knows. All my parts are here except for the CPU and I'm getting really psyched. Can you elaborate on why VT-D?

[Johnm]

If your build is only gong to be 3-4 drive you do not need VT-d..

 

If you do RMD drives, you have to do the extra step of RMD'ing each drive one at a time and for every drive change/upgrade. unRAID just sees it as a drive. if there was data already on it it "should" just pass that data through with whatever data is on it. I honestly only would consider that for a mini sized box or a test box.

 

It is honestly a Pain in the butt and I would recommend VT-d and full passthough if you can.

 

you have got one heck of a server board there, it just seems a waste to not fully utilize it.. (and yes i have the same board with an I3. I am wasting a board myself)

 

Also, you are correct the Xeon is 3 times the price, but you do get about 4 times the  power. I am not sure how well a low power dual core CPU without hyperthreading would work with more then a couple of guests. you might tax that CPU rather quickly.

 

EDIT: look at TIP#3 to get an idea of the  work involved. http://lime-technology.com/forum/index.php?topic=14695.msg138466#msg138466

 

EDIT2: you can get an E3-1220L (an I3 with VT-d and no video) for $199 http://www.mwave.com/mwave/SKUSearch.asp?px=FO&scriteria=BA48250  

If I did that, I would probably just fork up the extra $40..

[wbburden]

I picked up that motherboard on a NE Open Box sale for $108. The I/O shield was missing but eBay had that for $4.

 

So without a SATA controller, don't I have to manually deal with each individual drive anyways vs. adding the card as a single unit? If so, this might just come down to a potential performace question when comparing the 2 CPUs.

 

 

 

[Johnm]

If you do not have a sata controller, you would have to RMD the drive anyways.

 

If you had a sata controller and VT-d, you passthough the entire sata controller and be done with it. you could hot swap drives all day and it wont care (hardware wise).

[wbburden]

I got to thinking about this last night after my last post. I'm wondering if the motherboard has controller that is presented to ESX for the local drives or if each drive is seen individually. I wish I had another 1155 chip so I could test this.

[Johnm]

the motherboard controller is a single device (with 6 ports).

 

If you pass it through (and it can be), you would loose the datastore drive by passing it to the unraid guest.  This would result in killing your ESXi server requiring a rebuild of ESXi (the unraid data would still be good).

 

You would still need a some sort of add-on drive controller for VT-d and unRAID.

 

you can see the cougar 6port SATA controller here:

[wbburden]

I think I understand. You've cleared up a lot for me. Thanks for the good info here and in your Atlas thread.

[Johnm]

I can not guarantee it would work, but in theory it should.

you could put the datastore on some low end 2 port PCIe controller and pass the onboard controller to unraid.

It wont be ideal, but you said  only a few guests and it is cheaper then an HBA.

 

With some motherboards you get strange issues when you passthough motherboard items. like loss of video or usb ports.

In most cases though, it is fine. I have not tested it with this motherboard.

I also don't think I will at this point.

 

You could always just get the  I3 now. Use RDM.. maybe a few months down the road when your budget is better, build an HTPC , Backup box or desktop with the I3 (or sell it) and pick up a Xeon and go VT-d then.