Dell PowerVault MD3000i Dell MD Storage Array vCenter Plug-in User’s - Page 29

You might want more, smaller LUNs for the following reasons: • Less wasted storage space. • Different applications might need different RAID characteristics. • More flexibility, as the multipathing policy and disk shares are set per LUN. • Use of Microsoft Cluster Service requires that each cluster disk resource is in its own LUN. • Better performance because there is less contention for a single virtual disk. When the storage characterization for a virtual machine is not available, there is often no simple answer when you have to decide on the LUN size and number of LUNs to use. You can experiment using either predictive scheme or adaptive scheme. Using the Predictive Scheme to Make LUN Decisions When you plan how to set up your storage for your ESX/ESXi systems before you format LUNs with VMFS datastores, you must decide on the LUN size and number of LUNs to use. To make LUN decisions using the predictive scheme: 1 Create several LUNs with different storage characteristics. 2 Build a VMFS datastore on each LUN, labeling each datastore according to its characteristics. 3 Allocate virtual disks to contain the data for virtual machine applications in the VMFS Datastores built on LUNs with the appropriate RAID level for the applications' requirements. 4 Use disk shares to distinguish high-priority from low-priority virtual machines. 5 Disk shares are relevant only within a given host. The shares assigned to virtual machines on one host have no effect on virtual machines on other hosts. 6 Run the applications to determine whether virtual machine performance is acceptable. Dell MD Storage Array vCenter Plug-in 29