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telos888
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VMotion Licensing Problems and Shared LUN

Hello,

Here is a problem that has me stumped, maybe someone here can help me figure this out. I have two ESX 3.0.1 Servers here, with a single VirtualCenter 2 Server. Both ESX Servers are using an Adaptec SnapServer 110 iSCSI target for VMFS storage as they are IDE only machines. When I originally went to do the install, VMware ESX was not able to discover more than one iSCSI LUN, even though I created a total of 12 on the iSCSI target. I have no idea why, it seems to me that ESX should provide you with a list of remote targets then allow you to select the one you want, but apparently that's not possible. Anyway, ESX would not allow me to even edit by hand the iSCSI target, so I had to go back and delete the entire RAID volume, then create separate volumes, each with a separate iSCSI target, in order to get both ESX servers using the Adaptec SnapServer as an iSCSI target.

So now everything is working insofar as two ESX Servers with VMFS storage on the Adaptec SnapServer; however, VMotion only shows up as "N/A". I am assuming this is because the iSCSI volumes are on separate LUNs? On the SnapServer, I have an option to allow multiple initiators. Does ESX Server have the ability to support multiple initiators on the same iSCSI LUN, ie if I just allocate the entire box to a single 500 gig iSCSI share, can I point all of the local ESX Servers at that box and have them share the same share without contention and/or locking issues?

Thanks in advance

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letoatrads
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Does ESX Server have

the ability to support multiple initiators on the

same iSCSI LUN, ie if I just allocate the entire box

to a single 500 gig iSCSI share, can I point all of

the local ESX Servers at that box and have them share

the same share without contention and/or locking

issues?

Thanks in advance

The answer to this is yes. That is how VMotion and HA work, all ESX servers must be able to see the same LUN's ( whether it is ISCSI or Fiber) in order for HA and VMotion to be possible. The concept behind VMotion is that the VMDK is on a shared storage medium that both servers access, and only the processes in memory are run locally on the host. When you initiate a VMotion that memory is mapped to the target server, copied, verified, and passed off where as the target server then accesses the VMDK and acts as the primary.

This is an over simplification, but I think you can see why the ESX servers would both need to have access to the same physical LUN and VMDK files.

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letoatrads
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Does ESX Server have

the ability to support multiple initiators on the

same iSCSI LUN, ie if I just allocate the entire box

to a single 500 gig iSCSI share, can I point all of

the local ESX Servers at that box and have them share

the same share without contention and/or locking

issues?

Thanks in advance

The answer to this is yes. That is how VMotion and HA work, all ESX servers must be able to see the same LUN's ( whether it is ISCSI or Fiber) in order for HA and VMotion to be possible. The concept behind VMotion is that the VMDK is on a shared storage medium that both servers access, and only the processes in memory are run locally on the host. When you initiate a VMotion that memory is mapped to the target server, copied, verified, and passed off where as the target server then accesses the VMDK and acts as the primary.

This is an over simplification, but I think you can see why the ESX servers would both need to have access to the same physical LUN and VMDK files.

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telos888
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Thanks for the answer. Another quick question - how can I set up a VMotion capable test environment using evaluation licenses? ie, do I need to have a separate license file for each ESX Server, or can I use the same one on each machine? I still haven't been able to get VMotion up and running, it appears to be a license issue now.

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letoatrads
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More than likely that is the case, if VMWare gave you an eval license for ESX and VC, you should have enough licenses to access multiple ESX Ent hosts. ( I think they gave me a 4 Proc ESX license)

Did you make sure to define a NIC for VMotion in the setup of each host? Until you define the IP for Vmotion, etc you won't be able try it.

Please feel free to award point to any answer you feel has been helpful!

telos888
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I used the VMkernel device to enable VMotion, which is attached to the gigabit network with its own IP address. It still shows up as "N/A" under VMmotion Enabled, on the Summary panel.

Do the machines to be migrated need to be in the same resource pool? All of the demonstrations I have seen have both ESX Servers showing up in the VI client, but I can't seem to figure out how to have everything populated under the same summary panel. I am logging in to each ESX server directly, is that where the VMotion live migration takes place, or does it need to happen somewhere else?

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Dave_Mishchenko
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When you added the licensing file for Vmotion, did you enable Vmotion on your hosts?

telos888
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I have it somewhat figured out. I had VMotion enabled, but I was logging into each ESX Server console instead of the COS for VirtualCenter. I have now successfully created a datacenter with both ESX Servers, and it appears I have the ability to live migrate with exception to the fact that the processor archs are different between the two ESX boxes, so no live migration was possible.

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