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JVirtual
Contributor
Contributor

NFS/iSCSI RDM

trying to run my windows vm's on nfs storage, AND create RDM's with iSCSI on the same vlan. received "nfsclient does not support creation of this type: 8" Sounds like this is not possible. Does anyone know if it CAN be done? or what another option will be. I

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9 Replies
DougBaer
Commander
Commander

I can't imagine why this would not be possible. I believe I have done this before in our lab for testing purposes.

I am assuming that you already have the NFS datastore mounted on the ESX host(s) and have the iSCSI software initiator configured.

Doug Baer, Solution Architect, Advanced Services, Broadcom | VCDX #019, vExpert 2012-23
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JVirtual
Contributor
Contributor

You are correct nfs mounted, iscsi configured.

Sent from Blackberry

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norregaard
Expert
Expert

You could try to configure the iSCSI storage on a separate vSwitch on a closed ip range (e.g. 192.168.1.x/24). That way you won't need another VLAN. You will, however, need to change the target ip's on the storage.

see here for a guide to configure the iSCIS:

http://www.vi-tips.com/2009/04/configuration-of-iscsi-in-vmware-vi3.html

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DougBaer
Commander
Commander

I just tested it in the lab and it works for me.

I have a simple config with one VMkernel port and both NFS and iSCSI presented to the ESX host from an EMC Celerra (NS20). Both datastores are visible and using the same network interface.

Doug Baer, Solution Architect, Advanced Services, Broadcom | VCDX #019, vExpert 2012-23
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JVirtual
Contributor
Contributor

Yes they are visible, but can you map a machine to an rdm thru the iscsi network?

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DougBaer
Commander
Commander

Interesting question. I think I missed that tidbit Smiley Wink

If I were going to do that, I would most likely load the iSCSI initiator into the VM's guest OS and directly map the iSCSI LUN from there.

Please stand by... I'll check :smileygrin:

Doug Baer, Solution Architect, Advanced Services, Broadcom | VCDX #019, vExpert 2012-23
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DougBaer
Commander
Commander

OK, I have presented the iSCSI RDM into a VM over the same VMkernel port as my NFS datastore is mounted -- not that I'd necessarily recommend doing this in production, but for testing, this works out.

I did encounter something odd that I'll have to look into. When the VM is hosted on my NFS datastore (boot VMDK and VMX files, etc...), I cannot add the iSCSI RDM. I go through the process and get a 'general system error occurred: internal error' message in VC. However, attempting to perform the same action with a VM that is hosted on local storage, it works fine.

???

Doug Baer, Solution Architect, Advanced Services, Broadcom | VCDX #019, vExpert 2012-23
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JVirtual
Contributor
Contributor

Strange, why would you not do this in production? The amount of traffic over one vlan?

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DougBaer
Commander
Commander

To be honest, I am more of an FC guy and don't hit iSCSI too much -- a combination of my background and technology preference. That, and I only have a few customers running RDMs anyway... the performance gain is questionable and it causes some other complications (such as SRM compatibility). From what I have read, there two camps of iSCSI users with regard to running the initiators at the ESX level vs. the guest level.

It appears that the mapping file needs to be on some sort of block storage in order for the RDM to function properly. I suppose you could present an iSCSI LUN to the ESX hosts and format it with VMFS, then use that to store the mapping files to the RDMs.

I recommend this article for all kinds of good ESX/iSCSI information

http://virtualgeek.typepad.com/virtual_geek/2009/01/a-multivendor-post-to-help-our-mutual-iscsi-cust...

Doug Baer, Solution Architect, Advanced Services, Broadcom | VCDX #019, vExpert 2012-23
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