ESXi and local storage questions

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WesM63

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I'm a complete noob when it comes to ESXi, so i might just be completely missing something.

I have a Dell Power Edge 1950 Gen 1 (Xeon 5148, 8Gb ram, 3x73gb Raid 5 on a Dell Perc 5i), currently running ESXi 4.1.0 Update 1.

Now, what my ultimate goal is, it to add another raid controller with a DAS. I want the DAS to only be used for a VM within ESXi. (Such as openfiler or freeNAS)

So, before i purchase the DAS I'm trying to get the same type of setup working with the internal Raid5. (the onboard perc5i).

What am i missing? I can see the free space that is not currently being used as a datastore or anything, but for the life of me I can't figure out a why to make it seen by the openfiler VM.

I don't know the technical terms, but lots more research has turned up Passthrough? It appears like what I want to do, but i have no idea.

Any help? TIA!


EDIT: I should mention, the Raid 5 array is partioned into 2 chunks. 30GB for ESXi and VM's and 100GB that i am trying to use for testing.
 
Passthrough is what you will want to accomplish your goals. However, there are the typical caveats.

1) the controller (onboard perc5i) needs to be either supported by ESXi 4.1 U1 for passthrough, or verfied to work by the community
2) the processor/chipset need to support VT-d which ultimately allows ESXi to pass the controller to the guest VM
3) (and this is probably killer for you) the whole controller goes to the guest, including all storage on it. you won't be able to split the array for both ESXi/datastore and pass the rest to a guest VM. passthrough is all or nothing.

with that said, I believe you could make the whole array part of the ESXi datastore, create a 100GB VMDK in the datastore, and place that on the guest's virtual SCSI controller (similar to the guest's boot disk). this is not something I have done, but there's no reason you can't do it. it may be frowned upon or performance may be poor. of these things, i am not sure. more seasoned users around here will be able to sound-off on the topic.
 
i'll also add that another solution (should you have an extra expansion slot) is to get a second supported controller. use one for the local ESXi install and its datastore (for VM storage) and configure the other for passthrough to your guest VM.

take a look at http://www.servethehome.com/configure-passthrough-vmdirectpath-vmware-esxi-raid-hba-usb-drive/ to have a look at your particular system to see if your controllers are recognized by the passthrough configuration screen within the vSphere client
 
jbraband,
Thanks for the info! I actually ran across that article. I think something must be turned off or disable or not even supported in the power edge 1950. (It's showing host does not support passthrough configuration on the VMDirectPath configuration tab)

At any rate, thanks for the info and i'll keep tinkering. I figured I would need a second Raid controller just for the DAS. The next question would be, what controllers work, providing the cpu/chipset supports it.
 
ooo....another option to get around the requirements for VMDirectPath (which it looks like your procs won't support) is to Raw Disk Mapping (RDM). I have 0 personal experience with this, but I hear it is very good performance (close to native) and is logically giving a guest access to a disk (or array i assume in the case of hardware raid controllers).

the difference here is that ESXi is in control of the HBA with its drivers and places a vmdk (i think) on the disk that fills it then passes that vmdk to the VM

this may be an option knowing that passthrough is a no go. although again, i don't know anything about the performance of this. but at the very least its another thing to google
 
Well if you're goin LGA771 path you need motherboard with 5400 chipset.

About ESXis local storage, atleast with perc 5/i the storage just seems to be slow. That's why i ended up building a separate iSCSI box for ESXis VM storage. ESXi is easily installable to USB stick.

Also i have not seen any reports about perc 5/i working succesfully with VMDirectPaht.
 
I believe this motherboard is a Intel 5500 chipset.

I suppose the easiest route would be to pickup a known supported raid card and see if it works. The upside is, if i can't get this to work, i can just return the server and build/buy one that will work.
 
jbraband said:
ooo....another option to get around the requirements for VMDirectPath (which it looks like your procs won't support) is to Raw Disk Mapping (RDM). I have 0 personal experience with this, but I hear it is very good performance (close to native) and is logically giving a guest access to a disk (or array i assume in the case of hardware raid controllers).

the difference here is that ESXi is in control of the HBA with its drivers and places a vmdk (i think) on the disk that fills it then passes that vmdk to the VM

this may be an option knowing that passthrough is a no go. although again, i don't know anything about the performance of this. but at the very least its another thing to google
Click to expand...

Hi!

I asked about the RDM performance vs native and RDM is slooooow. Check this post by _Gea
http://hardforum.com/showpost.php?p=1037204921&postcount=514
 
I agree. I tried RDM and it was as slow as vmfs filestore. Only passthru gave me near-native performance.
 
now that danswartz mentions it.....what i remember reading was about passthrough, not RDM. my bad.

I suppose it may be worth a test given no passthrough is available. poor performance > no performance.
 
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