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15 Cards in this Set
- Front
- Back
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ELB: SurgeQueueLength |
The total number of requests that are pending routing. The load balancer queues a request if it is unable to establish a connection with a healthy instance in order to route the request. For TCP/SSL listeners, all requests go through the surge queue, so it is common to have pending requests in the queue.The maximum size of the queue is 1,024. Additional requests are rejected when the queue is full. For more information, see SpilloverCount.Reporting criteria: There is a nonzero value.Statistics: The most useful statistic is max, because it represents the peak of queued requests. The average statistic can be useful in combination with min and max to determine the range of queued requests. Note that sum is not useful.Example: Suppose that your load balancer has us-west-2a and us-west-2b enabled, and that instances in us-west-2a are experiencing high latency and are slow to respond to requests. As a result, the surge queue for the load balancer |
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ELB: SpilloverCount |
The total number of requests that were rejected because the surge queue is full.[HTTP listener] The load balancer returns an HTTP 503 error code.[TCP listener] The load balancer closes the connection.Reporting criteria: There is a nonzero valueStatistics: The most useful statistic is sum. Note that average, min, and max are reported per load balancer node and are not typically useful. |
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Volume status warning
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Degraded (Volume performance is below expectations) Severely Degraded (Volume performance is well below expectations)
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Volume status Impared |
Stalled (Volume performance is severely impacted) Not Available (Unable to determine I/O performance because I/O is disabled) |
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HA: Elasticity |
Allows your application to "stretch" out and "retract" back in based off of utilizationPay-for-what-you-need concept |
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HA: Scalability. |
Focused on "Building out" the infrastructure to meet long term increase in capacity requirements (long term growth) Services: DynamoDB - S3 - EC2/Autoscaling - RDS - instance size |
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Auto Scaling Issues |
Security Group does not exist Key pair associated does not exist Auto scaling config not configured correctly Auto scaling group not found Availability zone no longer supported Instance type specification is no longer supported in AZ Auto scaling service is not enabled on your account Invalid EBS device mapping Attempting to attach EBS block device to instance store AMI Placement group attempting to use m1.large(wrong type). |
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Key RDS Metrics |
ReadIOPS WriteIOPS Read Latency Write Latency Database Connections DiskQueueDepth FreeStorage space ReadReplicaLag (Seconds) |
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AWS services : automated backups |
AWS RDS backup - Include automated backup solution Elastic cache has automated snapshot for redis cache cluster only |
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Elastic Load Balancer Cross AZ support |
You can use Elastic Load Balancers to load balance across different availability zones within the same region be not different regions (or different VPCs). |
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ELB Health check |
Ping Protocol Ping port Path (example /index.html) Responce Timeout in seconds Health Check interval Unhealthy threshold Healthy threshold |
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Sticky Sessions |
By default a load balancer routers each request independently to the application instance with the smallest load. However you can use the sticky session feature which enabled the load balancer to lock a user down to a specific ec2 instance. |
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Duration based Sticky Sessions |
Most commonly used, the load balancer itself creates the cookie. When the load balancer receives a request it first checks to see if the cookie is present in the request. |
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Application Controlled Sticky Session |
The load balancer uses a special cookie to associate the session with the original server that handled the request. |
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ELB : instance fails or becomes unhealthy |
The load balancer stops routing requests to that instance chooses a new healthy instance based on the existing load balancer algorithm. The load balancer will treat the session as now stuck to the new healthy instance even if the failed instance comes back. |
