* Liquidware has the following observations regarding vCPUs:

1. Liquidware has observed that the hypervisor sometimes does not schedule virtual machines with 4 vCPUs as often as it does for 1 vCPU or 2 vCPU machines. In these circumstances, it has seen performance improve if the appliances are allocated 2 vCPUs.
2. If the hypervisor is very lightly loaded and has a lot of free unallocated vCPUs available, 4 vCPUs or higher could help improve the overall user experience of the Stratusphere user.
3. The sizing recommendations are based on using high-end processors released in the last couple of years. Liquidware does not recommend using CPUs that are more than 3 years old.

** Liquidware has the following observations regarding Disk Storage:

1. The disk storage performance numbers noted were observed by Liquidware during internal testing. They represent the average sustained input/output operations per second (IOPS) required while inserting metrics and information (gathered by the Stratusphere Connector ID Keys) into the Stratusphere Database Appliance. Further, these performance values do not include the disk overhead necessary to support the execution of reports, administrative concurrency, or resource-intensive UI and API-based database queries. The numbers presented represent the minimum requirements for acceptable administrative user experience and overall performance of the Stratusphere Architecture.
2. The sizer assumes capturing the Top 20% of Application Processes using the most amount of resources. The sizer assumes the CID Keys are capturing data 24x7.
3. If sizing for Amazon Web Services, please note that the AWS storage devices may not be listed in alphabetical order when configuring your Stratsphere Hub AMI. Make sure the AWS label matches the Sizing Guide. For example, "/dev/sda1" is "HD 1", which is to be used for the operating system.

*** Liquidware generally recommends high availability for Collectors serving as CID Key Collectors only (not Network Collectors). This is enabled by default. Thus, the Sizing Guide calculations assume high availability for the CID Key Collectors. If high availability is disabled, then environments with less than 8,000 callbacks per hour will only require 1 CID Key Collector rather than the 2 CID Key Collectors we recommend for high availability. The recommendation increases with over 16,000 callbacks per hour.