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New

Add a Server Array

You can create two types of server arrays. Depending on which one you create (alert-based or queue-based) the configuration options will change accordingly.

Manage > Arrays > New

Index

A server array consists of mostly identical EC2 instances where the number of instances varies over time in response to changing factors. For example, the number of instances can go up based on high CPU usage, or go back down with low CPU usage. A series of alert specifications and escalations are used to define the conditions under which the server array will change, such as launching or terminating servers.

There are two types of server arrays:

  • Alert-based - These arrays are driven by user-defined alert specifications and escalations. When certain predefined conditions are met (ex: cpu usage > 80%), it triggers an alert escalation that performs a specified action (ex: grow the array) on the server array. An alert-based server array for a web application is commonly used for autoscaling, where additional application servers are launched and added to the server array to compensate for a sudden increase in server requests.
  • Queue-based - (These are EC2-only) These arrays are driven by queues and worker daemons. Queue-based arrays are commonly used for back-end batch processing tasks where the number of "worker" instances in an array will vary depending on the jobs in the input queue.

Select the New action button to create a new Server Array.

Manage > Arrays > Index

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Show

View basic information about the server array including its status, which deployment it's a part of, as well as any current scaling stats.

Action Buttons

  • Launch - Launch a single server into the array. Before enabling an array you should always launch a single server to make sure that all of the inputs are properly configured and that the server boots correctly.
  • Terminate All - Terminate all currently running servers in the array. You must also disable the server array if you want to prevent any new servers from being launched into it. Since this action can have a major effect on your Deployment, you will be prompted to manually type a phrase to confirm execution.
  • Clone - Clone a server array to make an editable copy.
Manage > Arrays > Show

Statistics tab

The Statistics tab is only visible for queue-based arrays that have statistics enabled. To view statistics, enable the "Audit entry analysis" option under the array's Info tab.

Manage > Arrays > Show > Statistics tab

Volumes tab

The Volumes tab lists all of the EBS volumes that are currently attached to instances in the server array.

Action Buttons

  • Attach Snapshot - When you attach a snapshot to a server array, that snapshot will be used to create a new volume and attach it to any new instances launched into the array. By default, the volume that gets created and attached to the instance will be deleted when an instance is terminated.
  • Attach Blank Volume - Create and attach a blank volume to any new instance that is launched into the server array. Specify the size of the volume in GB.
Manage > Arrays > Show > Volumes tab

Inputs tab

The Inputs tab shows the input values that will be inherited by all new servers that are launched into the server array. In most cases, new servers will inherit these values from the ServerTemplate and/or Deployment that it's attached to. Similar to a server's Next Inputs tab, any inputs that are defined at the Server Array level (under this tab) will overwrite any values that are defined at the ServerTemplate or Deployment levels. Remember, since servers in an array may have been launched at different times, this tab is not designed to be an accurate description of the input configurations for each server in the array.

Note: When you execute a script under a server array's Scripts tab, the inputs that are defined under this tab will be used.

Manage > Arrays > Show > Inputs tab

Info tab

The Info tab shows basic information about the server array including its status (enabled/disabled), the array type, associated deployment, autoscaling parameters, etc. If you can click the Edit icon to change the revision of the array's ServerTemplate, new servers will use the new revision specified while any existing (running) servers will inherit the input values of the new revision (input hierarchy rules apply). If you enable an array, new servers can be launched into the array. If you disable the array, no new server instances can be launched, but any active servers in the array will continue to run normally. The Scaling Stats section describes recent scaling activity.

If you are using an alert-based server array and have predictable traffic patterns, you might want to use the Schedule alert option to define a weekly scaling schedule.

Manage > Arrays> Show > Info tab

Current Alerts tab

The Current Alerts tab shows each running server that's in the array along with the status of its alerts. A green ball denotes that there are no triggered alerts, whereas a red ball denotes a triggered alert condition on the server. A red ball will be shown for each triggered alert specification.

Alert specifications cannot be edited under this tab. To modify alerts on the current running servers in the array you must modify them at the individual server level. To modify alerts on future servers that are launched into the array, use the array's "Next Alerts" tab.

Manage > Arrays > Show > Current Alerts tab

Scripts tab

The Scripts tab shows a list of RightScripts that can be run on server instances in the array. When you run a script on server instance(s) in the array using one of the options below, you will be prompted to verify input parameters and confirm the execution of the script. When you attempt to run a script, you will see a list of all ServerTemplates in the array that contain that script. You can only run a script on a server instance where its ServerTemplate contains the script. For example, there may be situations where you have server instances in the array that were created with different ServerTemplates or different revisions of the same ServerTemplate.

Action Buttons

  • run on oldest - Executes the script on the "oldest" server in the array.
  • run on all - Executes the script on all servers in the array.
  • run on remaining - Executes the script on the remaining servers. This option is only visible after you've used the 'run on oldest' option. The script will only be run on the remaining servers that exist when the button is pressed. If your array scales-up or down between the execution of both actions, the number of instances listed may not be accurate.
  • cancel - Cancel script execution.
Manage > Arrays > Show > Scripts tab

Instances tab

The Instances tab allows you to sort by the state of the active instances in the array (all, stranded, pending, operational, terminating). You cannot 'lock' an instance in a server array to prevent it from being terminated. Server arrays are designed to either grow or shrink based on the defined alert conditions. Instances will automatically be launched and terminated as necessary. You can only control the minimum number of instances that should remain active in a server array. However, you cannot control which ones should remain active. If you want a particular server instance to persist and not be termianted, you must add it to your deployment. You cannot move a particular server instance from a server array into your deployment or vice-versa.

Manage > Arrays > Show > Instances tab

Next Alerts tab

The Next Alerts tab shows the alert specifications that will be inherited by any new servers that are launched into the server array. By default, instances will inherit these alert specifications from the array's ServerTemplate. However, you can also add additional alert specifications at the server array level. Existing instances that are already running will remain unaffected and will not inherit any additional alert specifications.

  • New - Add a new alert specification from scratch.
  • Import Alert - Import an existing alert specification that's already been defined. For example, you can select one of RightScale's predefined "default" alert specifications or one from a Server/ServerTemplate. Changes to the original alert specification will not affect the one you are adding at the server array level as they are separate from each other.
  • All shown - select all the alerts in the list view.
  • None - deselect all alerts in the list view
  • Copy alerts to all array instances - copy the selected alerts to all the current instances running in the array.
  • Delete - delete all the selected alerts from the current instances running in the array.
  • Apply to selected - apply the specified action to all alerts selected.
Manage > Arrays > Show > Next Alerts tab
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Last modified
23:27, 16 May 2013

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