5.2

For OS disks, your sizing estimates depend on how frequently you refresh and recompose the pool.
If you refresh your linked-clone pool between once a day and once a week, make sure that the Selected Free
Space can accommodate storage use between the Min Recommended and 50% Utilization estimates.
If
you rarely refresh or recompose the pool, the linked-clone disks continue to grow. Make sure that the Selected
Free Space can accommodate storage use between the 50 % Utilization and Max Recommended estimates.
For persistent disks, your sizing estimates depend on the amount of Windows profile data that users generate
on their desktops. Refresh and recompose operations do not affect persistent disks.
How View Manager Calculates the Minimum Sizing Recommendations
To arrive at a minimum recommendation for OS disks, View Manager estimates that each clone consumes
twice its memory size when it is first created and started up. If no memory is reserved for a clone, an ESX swap
file is created for a clone as soon as it is powered on. The size of the guest operating system's paging file also
affects the growth of a clone's OS disk.
In the minimum recommendation for OS disks, View Manager also includes space for two replicas on each
datastore. View Composer creates one replica when a pool is created. When the pool is recomposed for the
first time, View Composer creates a second replica on the datastore, anchors the linked clones to the new
replica, and deletes the first replica if no other clones are using original snapshot. The datastore must have the
capacity to store two replicas during the recompose operation.
By default, replicas use vSphere thin provisioning, but to keep the guidelines simple, View Manager accounts
for two replicas that use the same space as the parent virtual machine.
To arrive at a minimum recommendation for persistent disks, View Manager calculates 20% of the disk size
that you specify on the View Composer Disks page of the Add Pool wizard.
NOTE The calculations for persistent disks are based on static threshold values, in gigabytes. For example, if
you specify a persistent disk size of any value between 1024MB and 2047MB, View Manager calculates the
persistent disk size as 1GB. If you specify a disk size of 2048MB, View manager calculates the disk size as 2GB.
To arrive at a recommendation for storing replicas on a separate datastore, View Manager allows space for
two replicas on the datastore. The same value is calculated for minimum and maximum usage.
For details, see “Sizing Formulas for Linked-Clone Pools,” on page 109.
Sizing Guidelines and Storage Overcommit
After you estimate storage requirements, select datastores, and deploy the pool, View Manager provisions
linked-clone virtual machines on different datastores based on the free space and the existing clones on each
datastore.
Based
on the storage-overcommit option that you select on the Select Datastores page in the Add Pool wizard,
View Manager stops provisioning new clones and reserves free space for the existing clones. This behavior
ensures that a growth buffer exists for each desktop on the datastore.
If you select an aggressive storage-overcommit level, the estimated storage requirements might exceed the
capacity shown in the Selected Free Space column. The storage-overcommit level affects how many virtual
machines that View Manager actually creates on a datastore.
For details, see “Set the Storage Overcommit Level for Linked-Clone Desktops,” on page 110.
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