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Manage and maintain a VMware VMFS Datastore

Follow these steps to scan for new storage devices, create a Virtual Machine File System Datastore, mount and dismount a VMFS Datastore, and increase the size of a VMFS Datastore.

VMware makes it relatively easy to manage and maintain your Virtual Machine File System Datastores. For example, you can add storage to a VMware host, create new VMFS Datastores or change the size of an existing VMFS Datastore.

The steps required to perform these tasks vary depending on whether you're using vSphere Client or vSphere Web Client. For the purposes of this article, I'll discuss both techniques.

If you're using vSphere Client, then you need to select your server, click the Configuration tab and then select the Storage option within the Hardware section to access the list of VMFS Datastores.

In vSphere Web Client, you can access the list of VMFS Datastores by clicking on your host server, followed by Datastores.

Scan for new storage devices

If you've recently added physical storage to your ESXi host, there is a good chance the management interface won't initially recognize the disk.

To force the management interface to recognize the disk, click the Rescan All link. When the Rescan dialog box is displayed, make sure the Scan for New Storage Devices checkbox is selected, as shown in Figure A below, and click OK.

Rescan for new devices.
Figure A. You might need to rescan for new storage devices.

In vSphere Web Client, you can scan for new storage devices by clicking on your host and then choosing the Storage > Rescan menu options.

Create a VMFS Datastore

Once you complete the process of scanning for new storage, you can create a new VMFS Datastore on the storage device by clicking on the Add Storage link. When you do this, the wizard prompts you to choose the storage type. Select the Disk/LUN option and click Next. At this point, you should see the new storage device, as shown in Figure B below. Select this storage device and click Next.

Select the new storage device.
Figure B. Select the new storage device and click Next.

As you progress through the wizard, it asks you to choose the VMFS version and to specify the name of the Datastore you want to create on the new disk, as well as the size of the Datastore. Upon completion, the management interface will display the new Datastore, as shown in Figure C below.

In vSphere Web Client, click on the host server and then choose the Storage > New Datastore option from the menu. At this point, vSphere Web Client launches the New Datastore wizard.

New Datastore
Figure C. Create a new VMFS Datastore.

In vSphere Web Client, click on the host server and then choose the Storage > New Datastore option from the menu. At this point, vSphere Web Client launches the New Datastore wizard.

The wizard's initial screen asks you to specify the type of VMFS Datastore you want to create. Choose the VMFS option and click Next. From there, you need to specify your partition options and click Next, and then Finish.

Mount and dismount a VMFS Datastore

If necessary, you can take a VMFS Datastore offline by dismounting it. To do so, simply right-click on the Datastore and choose the Unmount command from the shortcut menu.


Learn to use VMware Datastores.

It's worth noting that you can only dismount a Datastore if no VMs reside on it. VMware also cautions admins not to perform any operation that causes I/O to occur within the Datastore when the dismount is in progress. When you're ready to bring the Datastore back online, you can mount it by right-clicking on the Datastore and choosing the Mount command from the shortcut menu.

You can accomplish the same thing in vSphere Web Client by selecting a Datastore, clicking on Actions and then choosing the All vCenter Actions command from the shortcut menu. This causes the client to display a submenu, which includes the Mount Datastore and Unmount Datastore options.

Increase the size of the VMFS Datastore

VMware enables you to increase the size of a VMFS Datastore when necessary -- the size limit will vary depending on what version of VMware you're running. To change the size of a Datastore, right-click on the Datastore and choose the Properties command from the shortcut menu. On the Properties screen, click the Increase button to launch the Increase Datastore Capacity wizard.

The first thing you need to do is to select the storage device that will provide the additional capacity for the Datastore. Upon making your selection, click Next. You'll now see a screen that details the Datastore's current size, as well as the amount of free space on the disk that you've selected. Take a moment to review this information and then click Next.

Now the wizard will ask you how much capacity you want to assign to the Datastore. You can use the maximum available space or you can use the Custom Space Setting, which enables you to specify the amount of space you want the Datastore to use.

Click Next once more and you'll see a summary of the options you've chosen. Assuming everything looks good, click Finish.

If you need to increase the Datastore size using vSphere Web Client, click on your Datastore and then click on the Increase Capacity button. When prompted, choose the option to add an extent to an existing VMFS Datastore. Click Next, choose the disk you want to use and then click Next again. Now, choose the amount of disk space you want to use and click Next, followed by Finish.

This was last published in August 2018

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