iSCSI IQN may have changed after upgrade to 7.0 U2

Last week I noticed some folks reporting that they had an issue with upgrades to 7.0 U2 from 7.0 U1. The issue they experienced was not being able to access their iSCSI Datastores any longer. I did some digging internally and found out there was a change in how we store the iSCSI IQN when the IQN is randomly created. Now note, this problem only exists for randomly created IQNs, so if you have a custom-named iSCSI IQN then you can stop reading here. If you have a random IQN and also have access control defined for your initiators, then you will want to read this if you are planning on upgrading.

Basically what happens if you upgrade from 7.0 U1 to 7.0U2 and you use a randomly generated IQN is that we regenerate the IQN after a reboot. What does that look like, well on VMTN user Nebb2k8 posted this:

7U1d = iqn.1998-01.com.vmware:labesx06-4ff17c83

7U2a = iqn.1998-01.com.vmware:labesx07:38717532:64

As you can see, the format also changed.

So if you lose (or lost) access after the upgrade, you simply copy the newly generated IQN and add it to the access control list of your storage system for the LUNs it applies to. Make sure to remove the old IQNs. Another option of course is to configure the randomly generated IQN as a custom IQN, this is pretty straightforward as shown below for “vmhba67”. You could create new IQNs, or you could re-use the randomly generated old IQNs if you want to keep them the same.

$ esxcli iscsi adapter get -A vmhba67

 vmhba67
   Name: iqn.1998-01.com.vmware:w1-hs3-n2503.eng.vmware.com:452738760:67

$ esxcli iscsi adapter set -A vmhba67 -n iqn.1998-01.com.vmware:w1-hs3-n2503.eng.vmware.com:452738760:67

If you would like to know more about this issue, make sure to read this KB article, or read this article by Jason Massae which also provides some PowerCLI code to get/set the IQN.