How to create target LUN on same datastore?

[talhajee]

In vnx5100 we have created two partitions (LUNs) which needs to be shared separately with 2 VM machines for clustering

The issue is here, I have assigned the LUN size to a new data storage. And when I  created RDM for a virtual machine I had to select the target LUN but I was not able to see the LUN which I am looking for ( the one which I have assigned to the data storage I have created).

The question is here:

Why the LUN which was assigned to the storage is not been shown in the list?

Do we need to create a separate LUN for the data store and a separate for target LUN in Vsphere with the same size  of the LUN in VNX?

What is the Target LUN in VMware ( vsphere client)?

regards,

[rickardnobel]

talhajee wrote:

And when I  created RDM for a virtual machine I had to select the target LUN but I was not able to see the LUN which I am looking for

Did you assign the LUN on the VNX to be visible for the guest VMs or from the ESXi hosts?

[talhajee]

FRom ESxi host

[a_p_]

Can you confirm the new LUN has been added to the appropriate host group on the VNX?

Does the LUN show up under "Configuration" -> "Storage Adapters" on the ESXi host (after Refresh/Rescan)?

André

[talhajee]

yes please refer to attached file

[a_p_]

You can use a single LUN either as a VMFS datastore or a RDM, but not for both. As soon as you create a datastore on the LUN (i.e. format it with the VMFS file system) you cannot use it anymore as an RDM. An RDM is seen by the guest OS and will be formatted with the guest's file system (e.g. NTFS for Windows).

André

[talhajee]

I am going to use SAN and VM for clustering . For clustering i am going to share SAN lun between two VM .For cluster i have created RDM and i have to store it on some datastore.

Please tell me if i have RDM of size 128 GB and datastore of 512 GB if i create RDM and store it on data store how much space it will occupied .128 of RDM and 128 (out of 512) from datastore.

Please clarify.

regards,

talha

[a_p_ · Accepted solution]

For a RDM and a VMFS datastore you need to create/present two separate LUNs to the ESXi hosts. What's stored on the VMFS datastore is only the RDM mapping file (this will be created at the time you add the raw LUN to a VM), which shows up with the size of the RDM LUN, but does not require disk space on the datastore (only a few bytes).

André