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Disk Usage of VM provisioned by Citrix MCS

Refer to the following finding on the Disk Usage of VM provisioned by Citrix MCS

Citrix Machine Creation Service (MCS) creates a snapshot of master the VM and it copies the full snapshot to the storage repository to serve as the master image (base disk).

When provisioning multiple virtual desktops or servers, MCS includes two types of disks: a differencing disk and an identity disk for each virtual machine.

Disk Usage of Master VM

We had provisioned an Master VM called CITRIX-MASTER-SRV with Windows 2019 Server Standard with latest patches and necessarily applications, like Google Chrome, Edge for Business and etc

Total disk size of the Master VM is 16GB (Thin Provisioned)

#Check the Actual Size of VMDK file
(Get-VM -Name $VM).ExtensionData.LayoutEx.file | ? Name -like "*flat*" | Select Name, `
@{N="Size (GB)";E={[math]::Round(($_.size)/1GB)}}

Name                                                  Size (GB)
----                                                  ---------

Snapshot is created on Master VM

Get-VM $VM | Get-Snapshot | Select VM, Name

VM                Name                   
--                ----                   

Base Disk called CITRIX-XenApp-baseDisk-datastore-1012 is created

[root@nuc8:/vmfs/volumes/5e201eef-487a44db-35e0-54b2038b8296] ls -lh
total 1920
drwxr-xr-x    1 root     root       72.0K Aug 22 15:39 CITRIX-MASTER-SRV
drwxr-xr-x    1 root     root       72.0K Aug 22 15:41 CITRIX-XenApp-baseDisk-datastore-1012

[root@nuc8:/vmfs/volumes/5e201eef-487a44db-35e0-54b2038b8296/CITRIX-XenApp-baseDisk-datastore-1012] ls -lh
total 16517120
-rw-------    1 root     root      100.0G Aug 22 15:41 CITRIX-XenApp-baseDisk-datastore-1012-flat.vmdk
-rw-------    1 root     root         529 Aug 22 15:41 CITRIX-XenApp-baseDisk-datastore-1012.vmdk
[root@nuc8:/vmfs/volumes/5e201eef-487a44db-35e0-54b2038b8296/CITRIX-XenApp-baseDisk-datastore-1012] du -h
15.8G   .

Disk Usage of VM provisioned by Citrix MCS

New VM called CITRIX-APP01 is provisioned by Citrix MCS from Master VM

The are 2 x Disks attached to CITRIX-APP01 – A differencing Disk and an Identity Disk

Get-VM $VM | Get-HardDisk | Select FileName, Persistence, CapacityGB 

Filename                                                                                          Persistence CapacityGB
--------                                                                                          ----------- ----------
[LOCAL] CITRIX-APP01/CITRIX-APP01-1509517a-3e24-4fb4-bfdd-e996f649beb1-xd-delta.vmdk IndependentNonPersistent        100
[LOCAL] CITRIX-APP01/CITRIX-APP01_IdentityDisk.vmdk                                                Persistent   0.015625

Disk Usage of VM provisioned by Citrix MCS

The total size of CITRIX-APP01 is only 4.4GB

  • 4GB swap file which is equal to the size of vRAM assigned
  • Delta Disk only consumed 400MB when the VM is provisioned by Citrix MCS
[root@nuc8:/vmfs/volumes/5e201eef-487a44db-35e0-54b2038b8296/CITRIX-APP01] ls -lh
total 4663296
-rw-------    1 root     root        4.0G Aug 22 15:48 CITRIX-APP01-1459a410.vswp
-rw-------    1 root     root      407.0M Aug 22 15:41 CITRIX-APP01-1509517a-3e24-4fb4-bfdd-e996f649beb1-xd-delta-sesparse.vmdk
-rw-------    1 root     root         538 Aug 22 15:41 CITRIX-APP01-1509517a-3e24-4fb4-bfdd-e996f649beb1-xd-delta.vmdk
-rw-------    1 root     root      718.3M Aug 22 17:18 CITRIX-APP01-1509517a-3e24-4fb4-bfdd-e996f649beb1-xd-delta.vmdk-sesparse.REDO_365reu
-rw-------    1 root     root         418 Aug 22 15:48 CITRIX-APP01-1509517a-3e24-4fb4-bfdd-e996f649beb1-xd-delta.vmdk.REDO_365reu
-rw-r--r--    1 root     root         245 Aug 22 15:41 CITRIX-APP01-5597dd92.hlog
-rw-------    1 root     root      264.5K Aug 22 15:50 CITRIX-APP01.nvram
-rw-r--r--    1 root     root         180 Aug 22 15:41 CITRIX-APP01.vmsd
-rwxr-xr-x    1 root     root        3.3K Aug 22 15:48 CITRIX-APP01.vmx
-rw-------    1 root     root           0 Aug 22 15:48 CITRIX-APP01.vmx.lck
-rwxr-xr-x    1 root     root        3.2K Aug 22 15:48 CITRIX-APP01.vmx~
-rw-------    1 root     root       16.0M Aug 22 15:55 CITRIX-APP01_IdentityDisk-flat.vmdk
-rw-------    1 root     root         560 Aug 22 15:48 CITRIX-APP01_IdentityDisk.vmdk
-rw-r--r--    1 root     root      187.5K Aug 22 17:18 vmware.log
-rw-------    1 root     root      110.0M Aug 22 15:48 vmx-CITRIX-APP01-341419024-1.vswp
[root@nuc8:/vmfs/volumes/5e201eef-487a44db-35e0-54b2038b8296/CITRIX-APP01] du -h
4.4G    .
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