Reg:// doubt in Command view EVA.

[sandilyan]

Hi all,

i am present vdisk to server. In Present Vdisk Tab in right hand side. There will be a four tab "Present Vdisk" "Select None" "Select All" "Assign LUN" and "Cancel"

My doubt:
What is different b/w "Present Vdisk" and "Assign LUN" ?

Don't tell this two or same. if same tell me reason ?


Thanks
Sandilyan S

[IBaltay]

Hi,
assign LUN is giving you the opportunity to assign the LUN id of your choice to the vdisk.

[Uwe Zessin]

If you press the first one, the EVA decides to which LUN address to map the virtual disk. That is quick and easy if you deal with a new/single server.

If you press the other one, you can select a free address. That is necessary in some environments e.g. when you make changes in a VMware ESX environment, because a virtual disk must be presented to the same LUN address for all servers.

[Sivakumar MJ._1]

First Process is Present Vdisk and the Assign LUN

When you create a VDISK it has to be presetned to a host. The host will identify the Vdisk using the LUN Number, UUID, WWN LUN Name and the EVA will decide the LUN address for the VDisk automatically, else you have to use this option to Assign LUN.

You cannot ASSIGN A LUN number without the vdisk presented to a host.

If you try you will get "You must select a host to assign a presentation LUN"

[Uwe Zessin]

> UUID

The UUID is hidden within the EVA, cannot be changed and is not visible to a host.

Initially, the value of the UUID is copied to the LUN WWN, but it (the WWN) can be changed as long as the virtual disk is not presented.

Careful when doing this, because it has format requirements and can have negative effects to operating systems which use the value, f.ex. for binding purposes: examples are Tru64 Unix and VMware ESX.