# Calculations In this section we review metrics and calculations provided on the Replex dashboards. Here is a list of all the calculations described in this section: * Forecasted cost * Cost previous 30 days * Total cost * Idle cost * Savings * Utilized cost * Cluster score * CPU * RAM * Storage * Attached Node Disks ### Forecasted Cost **Next 30 days forecast** is a prediction of the next month’s costs based on the historical data of the past 7 days. ![Next 30 days forecast](/files/-MFf2OyoIsY7F-RZZSOq) ### Costs previous 30 days **Costs previous 30 days** are the total costs of the cluster resources (VM instances, storage) for the past 30 days. ![](/files/-MFf2lcts4QpR9YEfWdx) ### Total cost **Total Cost** is calculated as the sum of **Idle Cost** and **Utilized Cost**. For example **Cluster Total cost** is calculated as the sum of **Idle Cost** and **Utilized Cost** of all resources in that cluster. ![Cluster Total Cost](/files/-MFf39rJ911ugKWwspTF) **Namespace Total cost** is calculated as the sum of **Idle Cost** and **Utilized Cost** for all pods running in that Namespace. ![Namespace Total cost](/files/-MFf64FhhnUcZ03pT2gA) Similarly, **Team Total cost** is calculated as the sum **Idle Cost** and **Utilized Cost** for all pods labelled with that specific team. ![Team Total cost](/files/-MFf66UG9w7mj6h3ku0a) ### **Idle cost** **Cluster Idle cost** is calculated as the total cost of cluster resources that are unused. ``` idle cluster cost = idle CPU cost + idle RAM cost + idle PVC cost ``` In the above calculation the **Idle CPU cost** is a sum of idle CPU cost for all nodes belonging to the cluster. Similarly the **Idle RAM cost** is a sum of idle RAM cost for all nodes belonging to that cluster. ![Cluster Idle cost](/files/-MFf39rJ911ugKWwspTF) **Node Idle CPU cost** is calculated as the cost of un-utilized CPU on that node. ``` Node idle CPU cost = cost of un-utilized node CPU ``` Similarly **Node idle RAM cost** is calculated as the cost of un-utilized RAM on that node. ``` Node idle RAM cost = cost of un-utilized node RAM ``` Lastly, **Node idle PVC cost** is calculated as the cost of un-utilized Persistent Volume Storage provisioned for that cluster. ``` idle PVC cost = cost of un-utilized Persistent Volume Storage ``` ### Savings **Cluster Savings** represent the cost savings that can be made by optimising cluster resource utilization. ![Savings](/files/-MFf39rJ911ugKWwspTF) On the Replex UI **Cluster** **Savings** are calculated as the deviation of the **total cluster cost** from a best practice utilization baseline of 70%. ``` Cluster Savings = total cluster costs - (used costs / 0.7) ``` Here is an example to make this clearer: Assume we have a cluster with a **total cluster cost** of $100 and used costs of $25. In this scenario cluster savings are calculated as follows: ``` Cluster Savings = $100 - ($25 / 0.7) = $64.29 ``` This means that cluster costs can be reduced by $64.29, with a cluster utilization of 70%. Once optimised, the new cluster cost is $35.71. ``` New cluster cost = $100 - $64.29 = $35.71 ``` Similarly, the new cluster utilization is 70.01% ``` New cluster utilization = $25 / $35.71 * 100 = 70.01% ``` ### Utili**z**ed cost **Utilized Cost** is calculated as the sum of **Pod CPU cost**, **Pod RAM cost** and **Storage cost** for all pods. For example **Namespace Utilized costs** are calculated as the sum of **Pod CPU cost**, **Pod RAM cost** and **Storage cost** for all pods running in that namespace. ![Namespace Utilized cost](/files/-MFf6ZkugbWQ7Ehe1vWE) Similarly, **Team Utilized costs** are calculated as the sum of **Pod CPU cost**, **Pod RAM cost** and **Storage cost** for all pods labelled with that specific team. ![Team Utilized cost](/files/-MFf6gTW5HTGg0DNvu_n) ### Cluster score **Cluster score** is calculated based on how much resources were used within the cluster. The efficiency score is the deviation of actually used resources from the expected resources baseline. ![Cluster score](/files/-MFf4yqmDGBhtEEtYWW7) ``` Expected resources baseline = used resources (100 - 30)% = 70% ``` where **30%** is allowed idle cost. #### Example If used resources are **58%** of total cost: ``` efficiency score = (1 - ((70 - 58) / 70)) * 100 = 83% ``` Note, that if used resources go above the requested resources, the efficiency will not exceed 100%, instead the idle costs will increase. #### Efficiency Score in the Replex Interface The icon next to the efficiency score is displayed in different colours, based on the actual score value. This ensures a quick overview of the general efficiency of the cluster, wether it is in the cluster list or on the cluster dashboard. ![](/files/-MFf5C1H_esjg-Bjv8E2) A score between 61 and 100 means that the available cluster resources are used in an efficient way. ![](/files/-MFf5EFWB-AFj-ZDoNMR) A score between 31 and 60 means that the cluster configuration should be improved. ![](/files/-MFf5GArRcaVQBPNSAGR) A score between 0 and 30 means that most of the resources in the cluster are idling and the cluster should be downscaled in order to safe money. ### CPU **Pod Requested CPU** is calculated as the sum of CPU requests for all containers in the pod. ![Pod Requested CPU](/files/-MFf9PYKLsocbVpp-k4K) Each container can request CPU resources either as a fraction (0.5) or as millicpu (500m) using `spec.containers[].resources.requests.cpu` In Kubernetes one CPU is equivalent to 1 vCPU/Core for cloud providers and 1 hyperthread on bare-metal Intel processors. Below is an example of a pod spec. The pod has two containers, each requesting 250 millicpu of CPU. The first container requests CPU resources as a fraction (.25), whereas the second requests CPU resources in millicpu (250m). ``` apiVersion: v1 kind: Pod metadata: name: frontend spec: containers: - name: app1 image: images.replex.example/app1:v2 env: resources: requests: memory: "64Mi" cpu: ".25" limits: memory: "128Mi" cpu: ".5" - name: app2 image: images.replex.example/app2:v3 resources: requests: memory: "128Mi" cpu: "250m" limits: memory: "256Mi" cpu: "500m" ``` **Pod Used CPU** is calculated as the sum of CPU resources consumed by all containers in the pod expressed as a percentage. ![Pod Used CPU](/files/-MFf9PYKLsocbVpp-k4K) **Pod CPU cost** is calculated as the sum of **Container CPU cost** for all containers in the pod. ![Pod CPU cost](/files/-MFf9PYKLsocbVpp-k4K) **Pod Minimum CPU Usage** is the minimum amount of CPU used by the pod during the selected time range. **Pod Maximum CPU Usage** is the maximum amount of CPU used by the pod during the selected time range. **Recommended CPU** is generated by the Replex system and is the recommended CPU requests value for that pod. Recommended CPU is calculated as follows: ``` Recommended CPU = (Average CPU usage + CPU Usage stddev) / % Target CPU Utilization ``` {% hint style="info" %} Target CPU Utilization in the calculation above is 70% {% endhint %} ![Pod Min, Max CPU Usage](/files/-MfhPJ5QR_gWRkC_hY_y) **Standard Deviation** outlined in the CPU column is the stddev in CPU usage for that pod during the selected time range. ![Standard Deviation in CPU Usage](/files/-MfhhI-kJSbHXl8GjM7A) **Container CPU cost** is the product of **node CPU cost** and the fraction of CPU resources consumed by the container during a specific time interval. ``` Container CPU cost = node CPU cost * fraction of container node CPU usage ``` **Node CPU cost** is calculated as the product of **CPU cost per core** and the total number of cores on that node, for a specific time duration. ``` node CPU cost = (cpuCoreHourly * cores of node) / 60 * interval duration in minutes ``` **cpuCoreHourly** (CPU per core per hour) costs are fetched from the cloud providers using Replex’s pricing API. ### RAM **Pod Requested RAM** is calculated as the sum of memory requests for all containers in the pod. ![Pod Requested RAM](/files/-MFf9PYKLsocbVpp-k4K) Memory requests are measured in bytes. Each container can request memory resources as a plain integer or as a fixed-point integer with one of these suffixes: E, P, T, G, M, K using `spec.containers[].resources.requests.memory.` Memory resources can also be requested as power-of-two equivalents: Ei, Pi, Ti, Gi, Mi, Ki. Below is an example of a pod spec with two containers. The first container has RAM requests of 128Mi whereas the second has RAM requests of 256 Mi. ``` apiVersion: v1 kind: Pod metadata: name: frontend spec: containers: - name: app1 image: images.replex.example/app1:v2 env: resources: requests: memory: "64Mi" cpu: ".25" limits: memory: "128Mi" cpu: ".5" - name: app2 image: images.replex.example/app2:v3 resources: requests: memory: "128Mi" cpu: "250m" limits: memory: "256Mi" cpu: "500m" ``` **Pod Used RAM** is calculated as the sum of memory resources consumed by all containers in the pod expressed as a percentage. ![Pod Used RAM](/files/-MFf9PYKLsocbVpp-k4K) **Pod RAM cost** is calculated as the sum of **Container RAM cost** for all containers in the pod. ![Pod RAM cost](/files/-MFf9PYKLsocbVpp-k4K) **Pod Minimum RAM Usage** is the minimum amount of RAM used by the pod during the selected time range. **Pod Maximum RAM Usage** is the maximum amount of RAM used by the pod during the selected time range. **Recommended RAM** is generated by the Replex system and is the recommended RAM requests value for that pod. Recommended RAM is calculated as follows: ``` Recommended RAM = (Average RAM usage + RAM Usage stddev) / % Target RAM Utilization ``` {% hint style="info" %} Target RAM Utilization in the calculation above is 70% {% endhint %} ![Pod Min, Max RAM Usage](/files/-MfhPJ5QR_gWRkC_hY_y) **Standard Deviation** outlined in the RAM column is the stddev in RAM usage for that pod during the selected time range. ![Standard Deviation in RAM Usage](/files/-Mfhhojt1NUi16dcsIq0) **Container RAM cost** is the product of **node RAM cost** and the fraction of memory resources consumed by the container during a specific time interval. ``` Container RAM cost = node RAM cost * fraction of container node RAM usage ``` **Node RAM cost** is the product of **RAM cost per core** and the total number of cores on that node, for a specific time duration. ``` node CPU cost = (ramGBHourly ram of node in GB) / 60 * interval duration in minutes ``` **ramGBHourly** (RAM per GB per hour) costs are fetched from the cloud providers using Replex’s pricing API. ### **Storage** **Pod Storage Capacity** is calculated as the size of the Persistent Volume Claim (PVC) that is provisioned for that pod. This number is based on the pod spec. ![Pod Storage Capacity](/files/-MFf9PYKLsocbVpp-k4K) **Pod Storage cost** is calculated as the cost of PVCs attached to that pod. ![Pod Storage cost](/files/-MFf9PYKLsocbVpp-k4K) **Total Pod cost** is calculated as the sum of **CPU cost**, **RAM cost** and **Storage cost** for all containers in that pod. ![Pod Total Cost](/files/-MFf9PYKLsocbVpp-k4K) ### Attached Node Disks **Node Disk Cost** is calculated with the standard GB price of the particular cloud provider. 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