Determining Overlay Disk Size

Determining Overlay Disk Size

Determining Overlay Disk Size

Each persistent and stateless desktop in the Hive Fabric system is comprised of two files.  The first, obviously is the Template file.  Some organizations refer to this as the Golden or Boot Image.  The second of the two files is the Overlay (or Delta) disk.  

Monitoring the growth of this overlay disk is important:
  1. The growth of the overlay disk is indicative of OS or application updates running on a VDI.  For stateless desktops, these updates should always be disabled and applied to the Template  instead.
  2. Overlay growth, depending on storage (SSD, NVME, RAM), can impact the performance of the desktop.
  3. Growth of the overlay disk can reduce the overall density of the host, when target disk storage is limited. 

Hive Fabric UI

The easiest way to check on the overlay disk size for your desktop pool VM's is using the Hive Fabric UI.
  1. Login to the Hive Fabric UI.
  2. From the Visualizer, select a single Desktop Pool or the Pool label under the main navigation.
  3. Click on the Refine button above the Virtual Machines pool in the Visualizer.
  4. If the desktop view is in Tile mode, select the Table button near the top right of page.
  5. While in Table view, scroll to the right and locate the column for Primary Disk.
  6. A Primary Disk for a Desktop Pool VM is the overlay disk, while for a Standalone VM this represents the entire OS disk.
  7. For a Desktop Pool VM, a rough guideline of 2GB should be the target for the overlay disk.
    1. Overlay disks smaller than 2GB indicate a well optimized template image.
    2. Overlay disks larger than 3GB may potentially indicate that some sort of software update is running on the pooled desktop.

Command Line 

To check the size of the Hive Fabric Overlay  disk:
  1. Login to the command shell of the associated Hive Fabric host (ssh via putty or similar),  and run df -h.
    From the image below, Local Disk and Local RAM mount points
    1. /zdata is the mount point for Fabric Local Disk Storage Pool
    2. /zram is the mount point for Fabric Local RAM Storage Pool

      From the image below, Identifying NFS mount points
    1. NFS mounts show with the mounted IP path on the left and mount point on the right (i.e. /mnt/b9a5fd4b-7996-4a91-94dc-890aaa44a8cd)
  2. Run ls -lh /zram/* (where /zram is the mount path to the storage where desktops are deployed).

    From the image below,  Important Desktop Pool information 
  3. The overlay disk is output in the /zram/8fed5aff-3ac5-4cbf-93e1-a7c7d15d24dc section (each UUID in the /zram/ path represents a different desktop pool)
    1. When an overlay disks grows past ~2-3GB, look for some sort of application or OS updates that continue to bloat this disk
Local Disk and Local RAM mount points
               

Identifying NFS mount points

Important Desktop Pool information