This might not be a new thing but I had a thought of writing an article regarding these filters while I was studying in my VCAP exams. I have tested these things in my test lab and I think it is good thing to write an article with my own experience.
There are four main storage filters in VMware:
- VMFS Filter
- RDM Filter
- Same Host and Transports Filter
- Host Rescan Filter
By default these filters are enabled and you can manually edit these filters under vCenter server settings.
Before that I would like to explain the main purpose and requirement of these filters along with the associate parameters which you can change manually and enable the functionalities.
This filter prevents you from adding a LUN which is already using by a different datastore. this parameter value is set to “true” by default and you can manually set this to false and enable to add any VMFS volume which is currently using by a different datastore. Obviously, there is a risk of data corruption and does not recommend to change these values unless you have a special requirement.
This filter prevents you from adding a RDM LUN to a Virtual Machine which is already using by a different Virtual Machine. Manually setting this filter to false and adding to a Virtual Machine can be a data loss or corruption of the original Virtual Machine.
Same Host and Transports Filter
This Storage filter prevents you from creating a datastore extent from an incompatible LUN.
Host Rescan Filter
How can we change these filters?
- Go to your Home page in the vSphere Management console and select “vCenter Server Settings” or select “Administration” and “vCenter Server Settings”
- Select “Advanced Settings” to view avialble parameters, as I said these parameters are set to “true” and not visible by default
Example of changing the Filters
I have a VM (XPVM_01) with RDM LUN attached and it does not allow to attach the Existing LUN to a different VM (XPVM_02), by default if there are now free RDM LUNs available the “RAW Device Mapping” option is grayed out
Feature is grayed out since there is no free LUN in my SAN
Now I’m going to set the “config.vpxd.filter.rdmFilter” with the value of “false”, click on “Add” to add the parameter
Once you add the parameter you can see it and click “OK” to continue
Now I’m able to add the existing RDM LUN which is mapped to my “XPVM_01” VM to the second VM which is XPVM_02.
Once you add this filters in to the advanced settings of your vCenter you can go back and change the values to “true” and it is visible in the list.
I hope you enjoyed my post and thank you for viewing ……