Release Notes

Data Drives
12 Best Practices for Implementing VMware vSphere in a Dell PS Series Storage Environment | TR1091 | v1.3
6 Data Drives
There are four primary ways to connect data drives to VMs in a VMware vSphere and PS Series storage
environment, assuming that the C:\ or /root drive of the guest OS is located on a VMFS datastore volume.
• VMDK on VMFS
• iSCSI in the guest (sometimes called direct connect, or storage direct)
• Raw Device Mapping (RDM)
• Virtual Volumes (vVols)
6.1 VMDK on VMFS
A VMDK disk on a VMFS volume is the most commonly used practice for data drives. This scenario involves
carving out additional space on a VMFS datastore and assigning it to a virtual machine.
Advantages:
• Easy to configure: Easily add storage to a VM from free space in existing datastores or provision
another datastore
• Viewable in vCenter: This keeps the administration overhead light, the data drive location is known
and it is easier to integrate vCenter commands, such as cloning, templates and Storage vMotion
• Does not require storage team interaction: As long as the datastore has free space, data drives can
be added to a VM without any storage interaction
• Allows for tiering of data drives to different VMFS volumes/pools based on workload: An example of
this is the root (OS) drive on the guest can be located on a datastore created on a 10k R50 volume
and a database drive on the guest can be located on a datastore created on a 15k R10 volume
• Uses vSphere MPIO to maintain the same performance benefits
• Able to leverage VSM to take hypervisor consistent snapshots of the VM and its associated data
6.1.1 VMDK on VMFS best practices
When configuring a VMDK on VMFS, use the following best practices to maintain performance.
Using vSphere Web client:
1. Right-click on the virtual machine where the data drive needs to be added.
2. Select Edit Settings.
3. In the Virtual Hardware tab, select SCSI Controller from the New Device drop-down list, and click
Add. As many as three additional SCSI controllers can be added across which new hard disks can be
spread.
4. In the Virtual Hardware tab, select New Hard Disk from New Device drop-down the list, and click
Add. Do this for each virtual disk to be added to the virtual machine.