Machine Creation Services (MCS) is an internal component in XenDesktop (aka CVAD) software, which is used to provision and manage your VDI. This management includes create, start, stop, reboot and delete a VDI from Citrix site and from your hypervisor. Using MCS, you can deploy any number of identical machines automatically in your hypervisor.
When creating a Citrix machine catalog, you have to select an image from your hypervisor and specify the number of VDIs to create. You have to select a hosting infrastructure and provide credentials to connect to that hypervisor. MCS uses these credentials to perform all above-mentioned tasks in the hypervisor.
MCS follows some steps when you update an existing catalog, or create a new catalog(with MCS). First, you have to create a VM in your hypervisor, add it to the domain and install all the required applications and Citrix VDA software. This is called “master image”.
Let’s see those steps in detail:
- MCS creates a snapshot for the master image you select. You can also create a snapshot manually on the master image with a meaningful name and select it. MCS naming conversion is Citrix_XD_CatalogName.
- A new provisioning scheme will be created by MCS if you are creating a new machine catalog.
- MCS creates a full copy of the snapshot and creates a preparation VM from it. MCS creates this preparation VM with network disconnected so that it will not create any issues with the original master image.
- The instruction disk is attached to the preparation VM and powered on. This instruction disk contains the steps of image preparation which includes enabling DHCP, Windows KMS rearm, MS Office KMS rearm (If MS Office is installed), and Personal vDisk inventory collection (if personal vdisk is created).
- Instruction disk reports the results to MCS. MCS then shuts down the preparation VM. It will move to the next step only if all the results are successful. Instruction disk is deleted.
- MCS detaches the OS disk from the preparation VM and deletes the preparation VM from the hypervisor.
- MCS creates and stores a full copy of the snapshot so that all the machines deployed in that catalog will have the same properties and configuration. When you create a new catalog or update an existing catalog, you will see the base disk copy notifications in your hypervisor’s recent tasks. If you have 10 datastores attached to the catalog, MCS copies this snapshot to all the 10 datastores in your hypervisor.
- To verify this, Goto the datastores configured for your catalog, and look for folders which has your MasterImageName_baseDisk_datastore-datastoreid. Example: Win10MasterImage-baseDisk-datastore-1111. Here Win10MasterImage is the name of the master image, “-baseDisk-datastore-“ are used as is, 1111 is the uid of the datastore.
- By now, all the datastores configured for your Citrix machine catalog, will have the updated master image snapshot. MCS will use this snapshot to deploy new VDIs to the Citrix catalog.
When you update the master image with Windows patching or any other application updates, and select the “update machine catalog” option in the catalog properties, all the steps given above are repeated.
By now, you should know the steps followed by MCS in creating a new catalog or updating an existing catalog.
Quick question: After you create the Citrix machine catalog successfully, if you delete the master image from your hypervisor, can you deploy new VDIs to the Citrix machine catalog?
Yes or no, Let me know in the comments.
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