anchor.diff:  
   The HighMem instance type is slightly faster for higher concurrency.  Furthermore, SSD disks are slightly faster also but come at a cost.
   
  -| Instance Type | Storage Type | Storage Size | Memory | vCPUs | Network Speed | Use                                    |
  -|---------------|--------------|--------------|--------|-------|---------------|----------------------------------------|
  -| n1-standard-8 | HDD          | 6TB or 3TB   | 30     | 8     | 10Gbit        | Dev/Test - Production                  |
  -| n1-standard-8 | SSD          | 1.4TB        | 30     | 8     | 10Gbit        | Dev/Test - Production                  |
  -| n1-highmem-8  | HDD          | 6TB or 3TB   | 52     | 8     | 10Gbit        | Dev/Test - Production                  |
  -| n1-highmem-8  | SSD          | 1.4TB        | 52     | 8     | 10Gbit        | Dev/Test - Production High Concurrency |
  +##### Master and Segment Instances
  +| Instance Type | Memory | vCPUs | Data Disks |
  +| ------------- | ------ | ----- | ---------- |
  +| n1-standard-8 | 30     | 8     | 1          |
  +| n1-highmem-8  | 52     | 8     | 1          |
   
   ## <a id="azure"></a>Azure
   
  
positive.code: net.ipv4.ip_local_reserved_ports=65330
  ```
  
  AWS requires loading network drivers and also altering the AMI to use the faster networking capabilities.  More information on this is provided in the AWS documentation.
  
  ## <a id="cd-storage"></a>Storage
  
  
negative.code: This variable is pretty simple.  Greenplum needs at least 8GB of RAM per segment process to work optimally.  More RAM per segment helps with concurrency and also helps hide disk performance deficiencies.  
  
  #### <a id="aws-network"></a>Network
  AWS provides 25Gbit network performance on the largest instance types, but the network is typically not the bottleneck in AWS. The "up to 10Gbit" network is sufficient in AWS.
  
  Installing network drivers in the VM is also required in AWS, and depends on the instance type.  Some instance types use an Intel driver while others use an Amazon ENA driver.  Loading the driver requires modifying the machine image (AMI) to take advantage of the driver.
  
  
  ### <a id="storage"></a>Storage
  
  #### <a id="aws-ebs"></a>Elastic Block Storage (EBS)
  The AWS default disk type is General Performance (GP2) which is ideal for IOP dependent applications. GP2 uses SSD disks and relative to other disk types in AWS, is expensive.  The operating system and swap volumes are ideal for GP2 disks because of the size and higher random I/O needs.
  
  Throughput Optimized Disks (ST1) are a disk type designed for high throughput needs such as Greenplum.  These disks are based on HDD rather than SSD, and are less expensive than GP2.  Use this disk type for the optimal performance of loading and querying data in AWS.
  
  Cold Storage (SC1) provides the best value for EBS storage in AWS.  Using multiple 2TB or larger disks provides enough disk throughput to reach the throughput limit of many different instance types. Therefore, it is possible to reach the throughput limit of a VM by using SC1 disks.
  
  EBS storage is durable so data is not lost when a virtual machine is stopped.  EBS also provides infrastructure snapshot capabilities that can be used to create volume backups.  These snapshots can be copied to different regions to provide a disaster recovery solution.  The Greenplum Cloud utility `gpsnap`, available in the AWS Cloud Marketplace, automates backup, restore, delete, and copy functions using EBS snapshots.
  
  Storage can be grown in AWS with "gpgrow".  This tool is included with the Greenplum on AWS deployment and allows you to grow the storage independently of compute.  This is an online operation in AWS too.
  
  #### <a id="aws-ephemeral"></a>Ephemeral
  
  Ephemeral Storage is directly attached to VMs, but has many drawbacks:
  - Data loss when stopping a VM with ephemeral storage
  - Encryption is not supported
  - No Snapshots
  - Same speed can be achieved with EBS storage
  - Not recommended
  
  #### <a id="aws-recommend"></a>AWS Recommendations
  
  ##### Master
  | Instance Type | Memory | vCPUs | Data Disks |
  | ------------- | ------ | ----- | ---------- |
  | r5.xlarge     | 32     | 4     | 1          |
  | r5.2xlarge    | 64     | 8     | 1          |
  | r5.4xlarge    | 128    | 16    | 1          |
  
  ##### Segments
  | Instance Type | Memory | vCPUs | Data Disks |
  | ------------- | ------ | ----- | ---------- |
  | r5.4xlarge    | 128    | 16    | 3          |
  
  Performance testing has indicated that the Master node can be deployed on the smallest r5.xlarge instance type to save money without a measurable difference in performance.  Testing was performed using the TPC-DS benchmark.
  
  The Segment instances run optimally on the r5.4xlarge instance type.  This provides the highest performance given the cost of the AWS resources.
  
  ## <a id="gcp"></a>Google Compute Platform (GCP)
  
  