One of the more common tasks you are likely to perform is to recompose a desktop pool to update the operating system or applications in the base image or, alternatively, to add new applications. It's always recommended to have test pools available for you to test updates prior to sending them out to your end users.

In this example, we are going to recompose one of the example desktop pools, but you could also perform a recompose operation on an individual virtual desktop:

1. To recompose a desktop pool, from the Horizon View Administrator dashboard screen, under the Inventory section in the left-hand pane, expand the option for Catalog, and then click on Desktop Pools. Double-click on the desktop pool on which you want to perform the recompose operation. In the example lab, we are going to select the Linked Clone desktop pool called Win7-Floating-lc. You will now see the details of the desktop pool in the Summary tab of the chosen desktop pool as shown in the following screenshot:

2. Click the View Composer button (1), and then from the menu options displayed, click on Recompose (2).

3. You will now see the Recompose screen and the Image option as shown in the following screenshot:

4. Here, you have the option to change the parent VM by clicking the Change... button (3). You can then select a new parent VM to recompose from. You would then see the snapshots that are associated with the newly selected parent VM in the table (4), from where you would then click it to select it.
5. You can just select a new snapshot of the current image. This would reflect an updated version of the existing image that you then created a new snapshot from. To do this, again click the snapshot you want to use (4).
6. Click Next > to continue.

7. You will now see the Scheduling screen where you can configure the time of the recompose operation, and what happens if users are connected at the time of the recompose. This is shown in the following screenshot:

8. The first option is to set the date and time that you want the recompose operation to start (5).
9. Next, you have the option to wait until users log off before the recompose starts. To enable this option, click the radio button for Wait for users to log off (6). Or you can click the radio button for Force user to log off (7), which will forcibly log users off. However, they may be given a grace period before actually being logged off to allow them to save any work.
10. You then have the option to check the box for Stop at first error (8). Check this to stop the recompose if there are any errors. This would prevent rebuilding all the virtual desktop machines in the pool if there are any problems.

11. If we just refer back to the force users to log off option, you can also configure a grace period before they are logged off. This can be edited in the Global Settings section as shown in the following screenshot:

12. To edit the global settings, from the Inventory pane on the left-hand side, expand out the option for View Configuration, and then click on Global Settings (10). Then click on Edit... (11), and in the General Settings box, scroll down to the highlight section (12). You can then configure the message and the grace period.
13. On the Recompose screen, now click Next > to continue.
14. You will now see the Ready to Complete box as shown in the following screenshot:

15. Check the configuration settings and then click the Finish button.
16. The recompose operation will now start depending on the start time configured and whether to wait for users to log off.

You have now successfully performed a recompose operation on one of the Linked Clone desktop pools in the example lab. In the next section, we will look at the refresh operation.