Something has been bugging me for some time now about vCenter disk performance statistics. Basically vCenter shows each SCSI LUN with a unique ID as per the following screenshot. When viewed through the disk performance view it’s impossible to tell what is what unless of course you know the NAA ID off by heart!?
I was working on a project this weekend putting a Tier 1 SQL server onto our vSphere 4.0 infrastructure, therefore insight into disk performance statistics was key. So I decided I needed to sort this out and set about identifying each datastore and amending the SCSI LUN ID name, here is how I did it.
Identify the LUN
First of all navigate to the datastore view from the home screen within vCenter
Click on the datastore you want to identify and then select the configuration tab
Click on the datastore properties and then select manage paths
Note down the LUN ID in this case 2 and also note down the capacity
Change the SCSI LUN ID
Now navigate to the home screen and select Hosts and Cluster
Select a host, change to the configuration tab and then select the connecting HBA
At the bottom identify the LUN using ID and capacity noted earlier and rename the start of ID. I chose to leave the unique identifier in their in case it is needed in the future.
Now when you look at the vCenter disk performance charts you will see the updated SCSI LUN ID making it much more meaningful and useable.
Raw Device Mappings
If you have Raw Device Mappings (RDM) attached to your virtual machine then these to are capable of showing up in the vCenter disk performance stats. It’s the same process to change the name of the SCSI LUN ID however it’s slightly different when identifying them. To do so carry out the following.
Edit the settings of the VM, select the RDM file, select Manage Paths and then note down the LUN ID for the RDM. Use this to identify the LUN under the Storage Adapter configuration and change it accordingly.
Following making these changes I can now utilise the vCenter disk counters to compliment ESXTOP and my SAN monitoring tools. Now I have a full end to end view of exactly what is happening on the storage front, invaluable when virtualising Tier 1 applications like SQL 2008.
There are a plethora of metrics you can look at within vCenter, if you would like to understand what they all mean mean then check out the following VMware documentation.