Elastic media server
All the replicas for the media server are always up and running which incurs unnecessary cost to customers. The basic media server pod power management (Elastic media server) feature provides Auto scaling of media server replicas based on the CPU and memory usage as well as the jobs queued due to maximum jobs per media server settings to reduce the cost.
Note:
For some of the cases such as import and duplication and so on, specifically selected elastic media server is ignored and is treated as any available media server. This is not applicable to cases where media server is used as backup host/client.
For enabling/disabling the auto scaling feature, following media server CR inputs are required:
: Describes the maximum number of replicas that the media server can scale up to.
: Describes the minimum number of replicas of the media server running. This is an optional field. If not specified, the value for field will be set to the default value of 1.
From version 10.5 and later, along with CPU and memory usage, the media server scaleout is also seen if the jobs are found in queued state due to the maximum job per media server settings. To configure this setting, refer to the configuration parameter bpsetconfig below.
To enable the elasticity of media server, the value of must be more than value of .
To disable the autoscaling feature of media server, ensure that the value of is equal to the value of .
Note:
The value of must be greater than 0 to enable the elasticity of media server.
NetBackup 11.0 and later, now provides support for scaling down the value of media server custom resource to 0 to diverge from the default behavior. After updating the value of there would be no media server pod running when there are no jobs running. This improves the total cost of ownership (TCO). The count of nodes reduces to 2 when the setup is idle. User must change the value of by editing the environment custom resource object.
When , user must change the minimum size of media nodepool to 0 through the portal.
If no existing media pod or external media is available, all jobs that require storage interaction will trigger the creation of a new media pod by the NetBackup operator. A job remains in queue/active state waiting for resource with the following reason till the time new media pod is up and ready:
Cloud scale media server is not available
Primary server acting as media server will not be used in such cases.
For more information on the above reason and the resolution for the same, refer to the following section:
Note:
For certain jobs, example big data workloads, a specific media server is required. Users must configure these jobs with minimumReplica = 1 in the media server custom resource. Same applies to other cases where media server used as backup host.
Following table describes the ElasticityAttributes that describes the attributes associated with the media server autoscaler. These attributes are only applicable if autoscaler is running.
Fields | Description |
|---|---|
ExpectedReplicas | Indicates the ideal number of replicas computed by media server autoscaler that must be running. Note: If autoscaler is disabled then is equals to . |
ActiveReplicas | Indicates the actual number of replicas that must be running to complete the ongoing operations on the media servers. Note: If autoscaler is disabled then is equals to . |
NextIterationTime | Indicates the next iteration time of the media server autoscaler that is, the media server autoscaler will run after NextIterationTime only. Default value is empty. |
ConfigMap
A new ConfigMap with name
nbu-media-autoscaler-configmapis created during deployment and the key-value pairs would be consumed for tuning the media server autoscaler. This ConfigMap is common to all the media server CR objects and supports the following keys:Parameters
Description
memory-low-watermark-in-percent
Low watermark for memory usage.
memory-high-watermark-in-percent
High watermark for memory usage.
cpu-low-watermark-in-percent
Low watermark for CPU usage.
cpu-high-watermark-in-percent
High watermark for CPU usage.
scaling-interval-in-seconds
Interval after which media server autoscaler should run.
stabilitywindow-time-in-seconds
CPU and memory usage is calculated between two time intervals. This key indicates the time interval to be considered for collecting usage.
stability-count
CPU and memory usages are calculated by averaging out on multiple readings. This key indicates the number of readings to be considered.
graceful-shutdown-interval-in-seconds
The time interval after which the media server autoscaler should run incase it is not able to scale in due to running jobs on media server pods.
delayed-scalein-notifications-interval-in-minutes
The time interval between two successive notifications in the event that a scale in does not occur.
Note:
If you are upgrading to latest version, change the default values of the following parameters: scaling-interval-in-seconds : "45" stabilitywindow-time-in-seconds : "5" stability-count : "3" graceful-shutdown-interval-in-seconds : "35" cpu-high-watermark-in-percent: "80"
bpsetconfig
A new entry has been added in the primary server
bp.confthat is consumed by media server autoscaler. This value applies to all the Cloud Scale Technology managed media servers.Parameters
Description
MAX_JOBS_PER_K8SCLUSTER_MEDIA_SERVER
Maximum number of jobs that can run on each media server. This value can be set using bpsetconfig CLI.
Media server scaling
Parameters
Description
Scale-out
If all the active media servers managed by the Cloud Scale Technology are at their capacity due to the maximum jobs per media server settings and if there are more jobs in queue, scale-out is performed and multiple replicas may get scaled out due to the media server settings.
Additionally, if there are no jobs in queue due to this settings and if the CPU or memory consumption in the specified value provided in configMap but if any existing media server is idle that is, no jobs are running on it, then scale-out will not be performed. If all the existing media servers which are ready have jobs running on them, media server autoscaler will scale out a media server pod.
Scale-in
If the CPU and memory consumption is below the specified values provided in configMap, media server autoscaler will scale in the media server pods. Ensure that the running jobs are completed.
Note:
The scale-in does not happen until there are jobs in the queue due to the maximum job per media server settings.
Note:
The media server autoscaler scales out a single pod at a time in case a scale-out happens due to CPU and memory usage. It may exit from the multiple pods in case the scale-out happens due to the throttled jobs. The media server autoscaler can scale-in multiple pods at a time.
Note:
If the scale-in does not happen due to background processes running on the media server, a notification would be sent on NetBackup Web UI after regular time interval as configured in the autoscaler ConfigMap. For more details, see the following section:
The time taken for media server scale depends on the value of configuration parameter. During this interval, the jobs would be served by existing media server replicas based on NetBackup throttling parameters. For example, Maximum concurrent jobs in storage unit, Number of jobs per client, and so on.
Cluster's native autoscaler takes some time as per attribute, which decides on the time a node should be unneeded before it is eligible to be scaled down. By default this is 10 minutes. To change this parameter, edit the cluster-autoscaler's current deployment settings using the following commands and then edit the existing value:
AKS: az aks update --resource-group $RESOURCE_GROUP_NAME --name $CLUSTER_NAME --cluster-autoscaler-profile scale-down-unneeded-time=5m
EKS: kubectl -n kube-system edit deployment cluster-autoscaler
Note the following:
For scaled in media servers, certain resources and configurations are retained to avoid reconfiguration during subsequent scale out.
Kubernetes services, persistent volume claims and persistent volumes are not deleted for scaled in media servers.
For scaled down media servers, the deleted media servers are also displayed on Web UI/API during the credential validation for database servers.
Based on the configured schedules, if a large number of jobs are expected to run at certain time, the maximum number of jobs per media server should be configured to ensure that the required number of media server pods are scaled out and the jobs are properly distributed.
For configuration related parameters, see 'Media server scaling' table in Configuration parameters
Starting from NetBackup version 11.0, elastic media servers have been enhanced to share the primary server certificate. This enhancement is a step towards creating a unified, logical media server entity in a Cloud Scale environment with the following changes:
: Elastic media servers will be now mapped to the primary server's host ID.
: The primary server will now manage the certificate renewal for all media servers.
The renewed certificate will now be shared across the elastic media servers.
: There will no longer be dedicated Host ID entries for elastic media servers, simplifying host ID management within the environment.
This design ensures consistency and streamlines the management of certificates and Host IDs, contributing to a more cohesive and scalable architecture for elastic media servers.
: Upon upgrading to version 11.0.x.x.xxxx, the existing elastic media server certificates and their corresponding host IDs will be deleted.
All media servers will then be mapped to the primary server's Host ID.
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