iSCSI IQNs and VMware ESXi

[wreedps]

Hello,

What is best practice for iSCSI when connecting multiple FreeNASs to ESX servers? I have 2 FreeNASs connected to 3 ESX hosts that are working just fine, both FreeNASs are using the default IQN "iqn.2005-10.org.freenas.ctl"

I just attempted to add a 3rd FreeNAS to ESX and 1 of the 3 hosts saw the datastore. All 3 hosts saw the new array under "devices" but I could not see the datastore. I googled and searched for a hour or so and finally came to the conclusion I had a IQN collision I believe. I gave the new 3rd FreeNAS a unique IQN, ""iqn.2005-10.org.freenas2.ctl" and BAM! Datastores on all 3 hosts.

I come from a FC world, so any iSCSI tips are appreciated.

What is best practices for what I am doing? Should I make the global IQN unique on each FreeNas?

 

[mav@]

IQNs in iSCSI (concatenated with some other things) are used alike to initiator/target WWNs in FC. The best practice is to have unique IQNs on every target and every initiator. IQN collision between different initiators is a known source of problems -- two VMware with equal IQNs can't connect to the same FreeNAS box, since iSCSI target thinks it is session reinstatement and kills the first one. IQN collision between different targets is also not good, since it may confuse initiators during target discovery stage.

Recommended practice for generation of worldwide-unique IQN is a concatenation of hosts/organizations's domain registration year, month and the host name in the reverse order.

 

[wreedps]

Anyone know of a IGQ generator on the internet?

 

[mav@]

https://tools.ietf.org/html/rfc7143#section-4.2.7.4

Domain name is used only to avoid collisions with other people using other naming scheme. If you don't have any, you may use any other's, including used by default iqn.2005-10.org.freenas as base, concatenating it with some random unique string.

 

[Mlovelace]

Anyone know of a IGQ generator on the internet?

Just do:

Code:

iqn.2016-01.org.freenas.ctl:(your MB serial #)

For each freenas box, be sure to not include the parentheses from the above.

 

[wreedps]

Good idea, thanks guys!