EVA 5000 LUN Presentation

[jhetrick]

Hi,
I have an EVA 5000 that I am responsible for and willingly admit I am not an expert. I have only had to create a couple of VDisks and now have an issue that I am unsure of. When I presented the LUN to the host it mapped it with two different LUN numbers...19 and 16 and I am sure this is not what it should do. The host system sees only the LUN 19, but I created a second VDisk and it assigned LUN 16...now I am concerned I cannot delete the new VDisk just in case it is associated to the other VDisk which has data on it.
For example:
VDiskProdVM06 is new and it now has LUN 19 and 16 presented

Presentations:
Hosts:
Server_C LUN 19
Server_D LUN 16

When I created another VDisk it presented as the following which I have not assigned data to:
Server_C LUN 16
I did not add the _D path yet just in case it selects a different LUN number as well!
I know this may not make too much sense so if I can clarify in any way I will. If you are use to the Command View Software, I am sure you know what I am talking about. My problem is I have data already mapped to the LUN 19â ¦so can I remove the second path LUN 16 and not have any issues? The host sees only LUN 19 that I can tell the _D path is just for failover.
Alsoâ ¦why would it assign a different LUN number? I do not see an option to change the LUN number when I configured it.
Any help is greatly appreciated oh and if anyone knows were to find a manual on this that would be great. I found the user guide and it has 1 page of information on what I am looking forâ ¦not much! I attached a screenshot of what I see.

[AWilliams_1]

Normally when a Vdisk is presented it selects the next available LUN number starting from LUN1. If you are presenting the LUN at the time of the VDISK creation (ie on the VDISK creation page) then you have to accept the default.
Normal practice is to create the VDISK in the first step, but dont present it (ie dont assign a host). Once the LUN is created you click on the PRESENT tab and then go through the process of presentation to selected hosts and you can also define the default controller. In this section you can explicitly define the LUN number on the page where you select the host.
The only important thing here is that each VDISK presented to a host must have a unique LUN number.
There should be no relationship between the 2 LUNs you have created, so you can remove it if you want too.
You dont say what OS the host is running, but if it is windows then you would need to do a reboot or rescan to see the new LUN.

[Rob Leadbeater]

Hi,

I don't understand why you appear to have two host entries for the same machine - you don't need to do that.

If the host has two HBAs then both of those should be listed under the same host entry. Presenting a LUN to that host, then takes care of the dual paths...

As mentioned previously, it's usually best to not let CV EVA automatically assign LUNs when creating a new Vdisk - ie don't select the host when you do the create. You can then manually select the Present tab and assign the LUNs as required.

Hope this helps. If not please attach more screenshots of the host entries. (as JPEGs if possible, rather than some version of Word, which some people won't be able to read).

Cheers,

Rob

[jhetrick]

Hi Rob,

Yes I agree it makes sense if you present it to the host then it would cover the dual paths, but since that was the way the previous person set this up we decided to go with that. I was wondering if you know of a user guide that explains the EVA 5000 a little more than the generic setup guide?

In addition, since you saw the screenshot can I remove the LUN 16 on the _D path since that is not correct? On the Host, it is mapped as LUN 19 not 16.

[Uwe Zessin]

If the LUN16-path is not in use, yes, you can remove the mapping.

As the name "VDiskProdVM06" suggests the use of virtualization -- what platform is being used? If it is VMware ESX I really recommend that you assign all WWNs that belong to one server to one Host entry on the EVA. In most situations ESX _requires_ that a vdisk is presented to the same LUN address on all paths.

Do not use the "LVM.DisallowSnapshot" hack to 'work around' this limitation in an EVA environment!

[Sheldon Smith]

If you have two host entries for a single host, with a separate entry for each HBA, I STRONGLY recommend slowly going through each host pair:
1) verify all host paths work.
2) verify any and all vdisks are presented with the same LUN number.
3) unpresent all vdisks from ONE of the host entries.
-- If using a preferred path, unpresent from the OTHER host entry.
4) note the WWPN in the now idle host entry.
5) delete the now idle host entry.
6) add the WWPN to the working host entry.
7) optionally clean up the host entry name, presumably from something like " " to simply "".