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This section presents a method to expand a VMFS by using the nondisruptive expansion capability of the PowerMax.
vSphere offers VMFS Volume Grow, which allows customers to increase the size of a datastore that resides on a VMFS volume without resorting to physical extent spanning. It complements the dynamic LUN expansion capability that exists in PowerMax storage arrays. If a LUN is increased in size, then VMFS Volume Grow enables the VMFS volume to dynamically increase in size as well. Often, virtual machines threaten to outgrow their current VMFS datastores. They must either be moved to a new, larger datastore, or the current datastore must be increased in size to satisfy the growing storage requirement. Before this capability, the option for increasing the size of an existing VMFS volume was to extend through a process called spanning. Even if the newly available space was situated upon the LUN which the original VMFS volume resided, the only option was to add an extent. A separate disk partition was created on the additional space, and then the new partition could be added to the VMFS volume as an extent. With VMFS Volume Grow, the existing partition table is changed and extended to include the additional capacity of the underlying LUN partition. The process of increasing the size of VMFS volumes is integrated into the vSphere Client.
Importantly, there are four options when growing a Virtual Machine File System in vSphere. The following options are available when expanding VMware file systems:
The recommended selection is the Use free space to expand existing extent option. Using this choice eliminates the need for additional extents and reduces the management complexity of affected VMFS.
The process to grow a VMFS by extending a PowerMax volume is listed below:
Note: A known issue exists where the vCenter may not recognize the resized LUN. The datastore cannot be expanded. If the user experiences this issue, expand the datastore through one of the individual ESXi hosts in the vSphere Client. Then, rescan the other ESXi hosts in the cluster.
The PowerMax supports dynamic, online expansion of all SRDF pairs except SRDF/Metro until PowerMaxOS release 5978.444.444 when online SRDF/Metro expansion is offered.
Note: SRDF/Metro Smart DR does not support online expansion of devices.
The following section presents the steps to dynamically expand an SRDF device.