Back To Basics – Configuring Storage: Managing VMFS Volumes (Part 3 of 6)

January 20

VMFS is VMware’s File System and its used primarily with device that present themselves as block SCSI devices such as disks/LUN/Volumes that are attached to a local RAID controller, FC or iSCSI Storage Arrays. It’s been in existence for many years, and comes in two main flavours VMFS3 and VMFS5. Current edition of vSphere support both version for backwards compatibility, and its this allows for different generations of ESX Host to reside in the same vCenter and allows for the ease of movement from the older VMFS3 format found in version 3 and 4 of vSphere, and VMFS5 which is found on vSphere 5.x and later. If you require VMFS datastore greater than 2TB in size you must use VMFS5.

VMFS is by design a clustered filesystem that allows for many ESX hosts within the same cluster to access the same shared storage. This is often a requirement for advanced features such as vMotion, High Availability (HA) and Distribute Resource Schedule (DRS).

In this part of Back To Basics, I look at formatting a VMS volume, Increasing the size of a VMFS volume (grow) and Upgrading a VMFS3 volume to VMFS5.


This blogpost has been updated with a video which demos managing iSCSI and NFS volumes – together with how to provision new storage using a Synology Diskstation as an example – it also covers the steps to format and grow a VMFS volume. If you’re watching the YouTube version – be sure to set the video to full screen – and use 720p with HD for best quality. If you prefer the native video is also on

Alternatively: Native Video

Formatting VMFS volumes

1. >Hosts and Clusters >Select your vCenter >Right-Click the DataCenter or Cluster

2. Select New DataStore and select VMFS

Screen Shot 2013-11-29 at 13.04.45.png

3. Type in a friendly name for the datastore, and select an ESX host to view the disks/LUNs. Next select the LUN you wish to format

Screen Shot 2013-12-06 at 16.12.57.png

4. Next select the VMFS version

Screen Shot 2013-12-06 at 16.30.06.png

5. Next select whether you wish to use all of the available partition space – in most case you just accept this default to use all the capacity

Screen Shot 2013-12-06 at 16.31.31.png

6. Click Next and Finish

Note: One way of validating that all the hosts have access to the datastore, is using the Connectivity and Multipathing view that appears on the properties of a datastore once it has been mounted by the hosts. This will allow you to confirm that the datastore is available to all the hosts in a given cluster for example.

Screen Shot 2013-12-10 at 12.33.41.png

Increasing the size of a VMFS Volume

Ever since VMware introduce vSphere 4.1 it has been possible to increase the size of a VMFS datastore, once the underlying LUN/Volume has been increased. This can be useful in circumstances where the LUN/Volume is becoming full and/or was undersized in the initial creation. The process begins by using the storage vendors management tools to increase the size of the LUN/Volume.

Screen Shot 2013-12-10 at 11.33.54.png

Screen Shot 2013-12-10 at 12.08.03.png

Once the LUN/Volume has been re-size, before a rescan of the affect hosts so they are aware of the increase in space, and use the “Increase” button to grow the VMFS datastore

1. Right-click a Datacenter/Host/Cluster, Select All vCenter Actions and choose the Rescan Storage

Screen Shot 2013-12-10 at 12.12.32.png

2. Next locate the datastore in the inventory – and in the Manage Tab and Settings Column – click the Increase button

Screen Shot 2013-12-10 at 12.16.53.png

3. In the subsequent windows you should see that the LUN/Volume has displays the new size, and Expandable it marked as having a state of Yes. This indicates that it is possible to grow the VMFS volume.

Screen Shot 2013-12-10 at 12.19.35.png

4. In the Specify Configuration dialog box, from the pull-down for Partition Configuration switch to Use Free Space to expand this datastore

Screen Shot 2013-12-10 at 12.21.39.png

5. Clicking Next and Finish should trigger the process by which the VMFS partition grows to use the new free space that was allocated earlier

Upgrading VMFS3 to VMFS5 Volumes

VMware ESX 5.x support VMFS3 to allow for backwards compatibility to the older versions of ESX that support a legacy version of the file system. The file system can be upgrade from VMFS3 to VMFS5 in place without any need to shutdown VMs. This isn’t the only method to decommission a VMFS3 datastore. Upgrade paths do allow the SysAdmin to use VMware’s Storage vMotion feature to relocate the files of a VM from VMFS3 to a VMFS5 datastore. Once the old VMFS3 volume is empty, the datastore can be deleted and the storage handed back to the storage pool on the array in question or the old VMFS3 datastore can be destroyed, and a new VMFS5 volume created. The critical consideration is ensuring there are no legacy hosts left in the environment which may try and fail to connect to a VMFS5 volume. VMware support backwards compatibility not forwards compatibility.

1. Select the datastore in the Inventory

2. Select the Manage Tab, Choose the Settings Column and the General options

3. Click the button to Upgrade to VMFS 5…

Screen Shot 2013-12-10 at 13.55.08.png

Note: This button only appears on VMFS3 datastores. Notice the version of VMFS is 3.60.

4. In the Upgrade to VMFS 5… dialog box select the datastore to be upgraded and click OK

Screen Shot 2013-12-10 at 13.56.54.png


Posted by on January 20, 2014 in BackToBasics

Comments Off on Back To Basics – Configuring Storage: Managing VMFS Volumes (Part 3 of 6)
%d bloggers like this: