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VDI environments are typically heavily biased towards writes. This bias occurs because once the VMs are booted, the I/O traffic includes mostly changes from each VM. The traffic consists of file changes, swap file writes, memory paging, and updates to user preferences. This traffic pattern makes VDI one of the more demanding applications.
During the steady-state portion of the testing, the write ratio was approximately 70%. This is a higher write ratio than most other workloads that a storage array would support.
Instant clones generate a large volume of traffic during the provisioning process due to the method used to create the VMs. Since the in-memory VMFork technology creates the machines quickly, the volume of traffic is significant. The I/O required to complete the creation is brief but large. Plan for bursts of high traffic when creating or refreshing instant clone machines.
Since instant clone machines reset on logout, as users log off, their virtual desktops refresh. This occurs throughout the workday and should be considered in the design.
For this design, three Instant Clone pools were used, with a dedicated Horizon Connection server per pool. This is to ensure load balancing across the connection servers. A randomization was applied to the login order to help spread the login load evenly across the connection servers to ensure best performance and behave more like a production scenario.